Genus- Streptococcous [Greek ‘Streptos’ means easily twisted, Latin ‘coccus’ means spherical bacterium, berry] is classified under family Streptococcaceae. A related group of bacteria were classified under genus Enterococcus (earlier Lancefield group D streptococci). More than 50 species recognised, some are pathogenic in animals and man.


Streptococcus is Gram-positive cocci, non-motile, and non-sporing bacteria. S pyogenes characteristically is a round-to-ovoid coccus 0.6-1.0 µm in diameter. They divide in one plane and appear (especially in liquid media or clinical material) in chains of varying lengths or in pairs.

Isolation, cultural characteristics, identification

Most streptococci are fastidious facultative anaerobes, and some are obligate (strict) anaerobes. Most require enriched media (blood or serum as source of catalase). Edwards’ medium can be used for bovine streptococci isolates. Optimum temperature is 37 0C. After 24 hours incubation on blood agar, colonies are about 1mm in diameter, circular and greyish in colour. Clonies may be Beta-hemolysis with complete lysis of red cells surrounding the colony or alfa-hemolysis with partial or “greening” hemolysis. Streptococcus species don’t grow on MacConkeys agar. Lancefield group D organisms such as Enterococcus fecalis and E. lactis grow on MacConkey agar.

A series of biochemical tests like bile /esculin test, optochin sensitivity, bacitracin sensitivity etc. are done for species identification. They are catalase, oxidase negative and ferment sugars produce mainly lactic acid and no gas. Latex agglutination test and PCR are used for species identification and are considered more sensitive than culture methods.

Streptococcal diseases:


Table 1: Some streptococcal diseases in animals and man

Isolation, cultural characteristics, identification
Type species Lancefield Group Haemolysis       on Blood agar Disease produced
Str. pyogenes A beta Sore throat, scarlet fever, erysepalas, rheumatic fever, septicaemia in man
Str. agalactiae B beta, alfa or non- haemolytic Mastitis in cattle,  meningitis and septicemia in human infants
Str. dysgalactiae C Alfa(Beta           or gamma) Mastitis in cattle, polyarthritis in lambs
Str.  equi  subsp. zooepidemicus C Beta Mastitis, pneumonia, navel infections                in              horse, seticaemia,suppurative conditions in cattle,lambs,  pigs  ,hae, pneumonia in dogs

nephritis in man

Str. equi C beta Strangles              in             equines- horse,mule,donkeys (Resp.tract infection)
Str.equisimilis C beta Strangles in horse, infection in other animals, URTI in man, endocarditis in man
Str. uberis ? Alfa      or     non- haemolytic Mastitis in cattle
Str. suis R Alfa,(beta          or non-hemolytic) Septicemia,  meningitis,  arthritis, bronchpneumonia

 Antigenic Types

Cell wall polysaccharide antigens originally identified by Rebecca Lancefield (1933) developed twenty one group-specific Lancefield serotypes (A-W, omitting I &J). Some group antigens are shared by more than one species; no Lancefield group antigen has been identified for S. pneumoniae and some other streptococci.

The cell wall also consists of several structural proteins. In group A streptococci, the R and T proteins may serve as epidemiologic markers, but the M proteins are clearly virulence factors associated with resistance to phagocytosis. Molecular typing like pulse field gel electrophoresis (PFGE) is also now developed.



Streptococcus produces pyogenic infections forming abscess and septicaemia. S.suis is non pyogenic, produces septicaemia, meningitis and pneumonia.Virrulence factors include enzymes and extoxins like hyaluronidase, Dnase, streptolysin S and streptolysin O, streptokinase, proteases but their specific role is poorly understood. Capsules in S.pyogenes, S.equi and S.pneumoniae are antiphagocytic. The cell wall M proteins of S. pyogenes, S.equi, and S. porcinus are also anti-phagocytic.

Streptolysin S is an oxygen-stable cytolysin; Streptolysin O is a reversibly oxygen-labile cytolysin. Both are leukotoxic, as is NADase. Hyaluronidase (spreading factor) can digest host connective tissue hyaluronic acid as well as the organism’s own capsule. Streptokinases participate in fibrin lysis. Streptodornases A-D possesses deoxyribonuclease activity; B and D possess ribonuclease activity as well. Protease activity is similar to that in Staph. aureus has been shown in strains causing soft tissue necrosis or toxic shock syndrome.


Transport media for specimens is used as the streptococcus does not survive dessication. Clinical signs are indicative in some infections. In strangles signs like fever (42 0C), cough, abcess, lymph node swelling in throat, purulent nasal discharge are seen. Abcesses may form in abdomen, lungs and brain in chronic form called ‘bastard strangles.

Direct microscopy of Gram staining from smears of pus/milk/other specimens may be done. Specimens may be subjected to culture and colonies identified by biochemical tests. Christie Atkins and Munch-Petersen (CAMP) test with beta haemolytic S. aureus may be done for S. agaclctiae which gives positive reaction with ‘arrow head’ pattern of complete hemolysis. Serology may is used like latex  agglutination  test. Polymerase chain reaction  (PCR) is developed for identification of many streptococcal pathogens.

Prevention and control

No effective vaccine available in most streptococcal infections. However, a live aroA gene – mutant vaccine licenced in Europe for strangles in horse. Antibiotics like penicillins/ampicliins may be used for treatment. However, some S.suis strains are resistant to penicillins. Clinically suspect animals should be isolated. Disinfection of premises and improve animal husbandry practices may decrease the prevalence of diseases.


Introduction and history of Microbiology; Classification and nomenclature of bacteria; Microscopy
and Micrometry; Bacterial stains and techniques; Structure and morphology of bacteria; Growth and
nutritional requirement of aerobic and anaerobic bacteria; Normal, opportunistic and saprophytic bacterial
flora: Types and sources of infection, method of transmission of infection. Pathogenicity, virulence,
determinants of virulence, Epizootic and enzootic diseases, bacteremia, septicaemia and toxaemia,
endotoxins, exotoxins, antitoxins, toxoids; Bacterial genetics (Mutation, Transformation, Transduction
and Conjugation), plasmids and antibiotic resistance. Study of the following bacteria in relation to
isolation, growth, cultural, morphological, biochemical and antigenic characteristics, epidemiology
and pathogenesis, pathogenicity, diagnosis, prevention and control of bacterial diseases caused by
following bacteria:
Staphylococcus; Streptococcus; Corynebacterium, Trueperella,Rhodococcus; Listeria and
Erysepelothrix; Bacillus; Mycobacterium; Clostridium, Actinomyces, Nocardia, Streptomyces and
Dermatophilus; Family Enterobacteriaceae (E.coli, Klebsiella, Salmonella, Yersinia, Proteus);
Pseudomonas and Burkholderia; Pasteurella, Mannheimia, Actinobacillus and Haemophilus,
Brucella; Vibrio; Campylobacter; Bordetella and Moraxella; Gram negative anaerobes: Bacteriodes, Dichlobacteria and Fusobacterium; Leptospira and other Spirochaetes;Mycoplasma, Coxiella,
Neorickettsia, Ehrlichia, Anaplasma, Rickettsia; Chlamydia and Chlamydophila Emerging, re-emerging and
transboundry bacterial pathogens.
Introduction, classification, general properties of fungi; Growth and Reproduction of fungi; Study of
following important pathogenic fungi in relation to their isolation, growth, morphological, cultural,
biochemical and antigenic characteristics, epidemiology, pathogenesis, diagnosis and control of fungal
diseases caused by following genera: Candida and Cryptococcus; Aspergillus; Penicillium;
Dermatophytes and Malassezia; Dimorphic fungi, Rhinosporidium and Sporotrichum; Mycetoma and
Zygomycetes; Mycotic mastitis and mycotic abortion; Mycotoxicoses
Basic concepts and scope of Recombinant DNA technology; Gene cloning, Cloning vectors and
expression vectors; Transformation and transfection; Southern, Northern and Western blotting;
Bioinformatics, Gene banks; Application of molecular and biotechnological techniques: Polymerase
chain reaction, Nucleic acid hybridization, DNA library, DNA sequencing and DNA fingerprinting; IPR.
Ethics and regulatory issues in Animal Biotechnology.
History of Immunology; Lymphoid organs, tissues and Cells: Types of Immunity; Antigens, hapten, epitope,
Specificity, T dependent and T independent Antigens, heterophile Antigens, cross reacting Antigens,
blood group Antigens, Mitogens and factors affecting immunogenicity; Adjuvants; Antibody:
Structure, physiochemical properties and functions of various classes of immunoglobulins, Theories of
antibody production; Hybridoma and monoclonal antibodies, Serological reactions. Major
histocompatibility complex (MHC) structure, function and gene organization; Structure of BCR and
TCR; Antigen processing and presentation; Complement system: activation pathways and biological
consequences; Cytokines: general properties, major types and function; Hypersensitivity: classification
and mechanism of induction; Autoimmunity; Immunotolerance; Concept of Immunity to Microbes,
Vaccines and other biological.
History of Virology; Introduction to viruses; Structure of Viruses; Classification of Viruses; Viral
Replication; Genetic and Non-genetic viral interactions; Virus-Cell Interactions; Viral Pathogenesis,
Oncogenesis, latency and immunopathology. Studies on General Properties, Antigens, Cultivation,
Pathogenesis, Epidemiology, Clinical Signs, Diagnosis, Prevention and Control of following Viruses
and Prions Causing Diseases in Livestock and Poultry: Birnaviridae: Infectious bursal disease virus;
Reoviridae: Rotaviruses, Bluetongue virus, African horse sickness virus; Paramyxoviridae: Newcastle
disease virus, Canine distemper virus, PPR virus; Rhabdoviridae: Rabies virus, Ephemeral fever virus,
Bornaviridae: Borna virus. Orthomyxoviridae: Swine, Equine, Avian Influenza Viruses. Coronaviridae:
Infectious Bronchitis virus, Transmissible gastroenteritis virus; Arterivirdae: Equine viral arteritis virus,
Picornaviridae: FMD virus, Duck viral hepatitis virus; Caliciviridae: Feline calici Virus, Togaviridae: Equine encephalomyelitis viruses; Flaviviridae: Swine fever virus, BVD virus; Retroviridae:
Visna or maedi virus, Equine infectious anemia virus, Lymphoid leucosis virus, Bovine leukemia virus.
Poxviridae: Capripoxvirus, Avipoxvirus, Cowpoxvirus; Asfarviridae: African Swine Fever Virus;
Herpesviridae: Bovine herpes viruses, Equine Herpes viruses, Infectious laryngotracheitis
virus, Marek’s disease virus, Pseudorabies virus, Malignant Catarrhal Fever virus; Duck Plague virus,
Adenoviridae: Infectious Canine Hepatitis virus, Egg Drop Syndrome virus, Fowl adenovirus,
Papillomaviridae: Papillomatosis, Parvoviridae: Canine parvoviruses, Feline panleucopenia virus;
Circoviridae: Chicken Anemia Virus: Prions: Scrapie, Bovine Spongiform Encephalopathy; Emerging, reemerging and transboundry viruses and Viral Infections.




  •  It is a unique organ that develops in mammalians for the development of the fetus.
  • It is an apposition of fetal membranes to the endometrium to permit physiological exchange
  • between the fetus and the mother.


The placenta is composed of two parts:
1. The fetal placenta or allantois chorion
2. The maternal placenta or endometrium


  • The yolk sac or amniotic chorion acts as primitive placenta for a few weeks in the early
    embryonic period.
  • Allantois develop as a diverticulum of hind gut and fuses with the chorion (trophoblastic
    capsule of the blastocyst) to form the chorioallantoic placenta.
  • The blastocyst gets attached to the endometrium and the fetal membranes including the
    allantois chorion develop during the first month or more of gestation.
  • At this time the villiform projections of the chorion and the maternal crypts in the
    endometrium are rudimentary, small and friable and the nutrition is from the uterine
  • The easy separation of the two structures i.e., (maternal and fetal placentae) is prevented,
    not until the end of the first third of gestation because they do not become sufficiently
    intimate and complex.



  •  In epitheliochorial placentas, (cow, sheep, mare and sow) where the interdigitation of
    microvilli of the chorion or trophoblast and endometrial epithelium are closely apposed, no
    extensive degeneration or deposition of fibrinoid is present.
  • Therefore, in the former an acellular mechanical barrier and in the latter, the absence of
    trophoblastic antigenicity offer reasonable explanations for the retention of the placental
  • The inability of the immunologically active maternal cells to penetrate in to fetal circulation
    may also be important.
  • The sire contributes half of the genetic make up of the fetus and placenta and hence there
    should be sufficient tissue incompatibility to induce an immune reaction in the dam and
    subsequent rejection of the conceptus.
  • Wynn postulated that the greater the trophoblastic invasiveness (man and rodents), the
    greater the necrosis of both the chorionic and endometrial tissue. As a result there is
    development and deposition of a mechanical acellular barrier of acid mucopolysaccharide
    in man and rats having haemochorial placenta.

Classification of Placenta:


  • A.Deciduate or conjoined, Seen in man and rodents and in a slightly modified form in the dog and
  • In this type, the decidua composed of portions of the maternal epithelium or endothelium, submucosa, decidual cells and the fetal placenta are shed at parturition leaving the portion of the endometrium
  • B.Indeciduate or Non-deciduate
    • Seen in swine, horses and
    • In this type, the fetal membranes and placenta are expelled at the time of parturition, leaving the endometrium intact except in ruminants in which only the surfaces of the carcuncles are devoid of epithelium after the caruncles sloughs about 6–10 days following



It is divided in to 4 general types based on their shape as:

  • Diffuse
  • Cotyledonary
  • Zonary
  • Discoidal
  • It is found in wide range of species, including pigs, horses, camels, lemurs, whales, dolphins, kangaroos and
  • The villi of the chorion are distributed more or less evenly over the entire surface of the chorionic
  • The villi interdigitate with corresponding depressions or villi in the uterine epithelium, and physiological exchange take across these
  • The most striking feature of the ontogeny of the fetal membranes in the pigs is that the membranes undergo a rapid and dramatic elongation between days 6 and 12 of gestation, during which time the 2 mm spherical vesicle grows in to a filament of up to 1 m in
  • This elongation is due to a proliferation of trophoblastic tissue
  • Although it is well recognized that the fetal placenta can produce gonadotrophic hormones during pregnancy in many species, the horse always appeared to be an exception to the general


  • The cotyledonary placenta is characteristic of the ruminants; instead of being uniformly distributed over the entire surface of the chorion, the chorionic villi are clumped together in to well developed circular regions known as cotyledons.
  • These cotyledons develop only in those regions of the chorion that overlie predetermined aglandular areas of the endometrium known as the
  • The fetal cotyledon and maternal caruncle unite to form a placentome and these placentomes are the only sites of maternal-fetal exchange, the inter-cotyledonary chorion being devoid of villi and unattached to the


  • It is characteristic of the carnivores, and is the result of an aggregation of chorionic villi to form a band that encircles the equatorial region of the chorionic sac.
  • It may be complete, as in dog and cat, or incomplete, as in
  • The yolk sac persists as a vestigial structure floating in the allantoic fluid, whilst the chorioallantois remains as an oblong, fluid filled sac, with its girdle of placental
  • Incomplete zonary placenta may resemble the single or double discoid type, but the zonary placenta always has a central or marginal effusion of the maternal blood (the haemophagous organ).


  • It is found in a mixed group of mammals, including man and mouse, bats and rats, rabbits, hares.
  • The chorionic disc may be single (man) or double (monkey).
  • We should remember, however, that not all primates have interstitial
Classification       based       on       the       tissues       or       structures       that       intervene between the maternal and fetal blood


  1. Epitheliochorial type: (Horse, Pig, Cow and Sheep)

In this six structures: the endothelium, connective tissue, epithelium of the endometrium and the trophoblast or the chorion, mesenchyme and and endothelium of the fetal tissue separate the maternal and fetal blood.

  1. Syndesmochorial: (Ruminants)

All tissues of the previous type are present with the exception of the maternal epithelium. The loss of uterine epithelium was previously considered to occur in the placentomes in this type by phagocytosis and cytolysis by the cells of the trophoblast.

  1. Endotheliochorial: (Dog and Cat)

This has four structures seperating the maternal and fetal blood. i.e., the endothelium of the uterine vessels and the chorion, mesenchyme and endothelium of the fetal tissues.

  1. Haemochorial: (Man and Rodents)




Classification of Chorioallantoic Placentas

Chorio Villous Pattern Maternal-Fetal


Loss of Maternal

Tissue at Birth

Pig Diffuse Epitheliochorial None (non-deciduate)
Mare Diffuse and Micro-


Epitheliochorial None (non-deciduate)
Sheep, goat,

cow, buffalo

Cotyledonary Epitheliochorial None (non-deciduate
Dog, cat Zonary Endotheliochorial Moderate (deciduate)
Man, monkey Discoid Hemochorial Extensive (deciduate

Placental Attachment

Attachment or fusion of the placenta to the endometrium of the uterus.

Species Day of Gestation

Cow 30 – 35

Ewe 18 – 20

Mare 50 – 60

Sow 12 – 20

Implantation is the invasion of the embryo into the endometrium where the embryo and placenta continue to develop. This type of placentation is observed in humans, primates and rodents. Dogs and cats have a semi-invasive placentation.

Placental Anatomy and Function

The primary function of the placenta is to accommodate the fetus throughout gestation and to allow for nutrient transfer from the maternal circulation to the fetal circulation so the fetus can grow and develop. It is important to remember that the maternal and fetal circulatory systems never mix. Additionally, the individual components of the placenta have specific functions.


Yolk Sac Nutrient supply for the early developing embryo. Becomes vestigial as gestation


Amnion Protects fetus from injury, provides lubrication for parturition, and serves as a

reservoir for urine and waste.

Allantois Fuses with chorion (chorio-allantoic placenta), carries blood vessels of umbilical

cord, which attaches fetus to allantois, and is a reservoir for nutrients and waste.

Chorion Attaches to uterus, absorbs nutrients from the uterus, and allows maternal/fetal

gas exchange. Produces hormones.


  • The placenta functions as a multi-organ performing many functions and substituting for the fetal:
    • Gastro intestinal tract
    • Lung
    • Kidney
    • Liver, and
    • Endocrine
  • In addition, the placenta separates the maternal and fetal organism, thus ensuring the separate development of the


  • The blood of fetus and dam never come in to direct contact. Yet, the two circulations are close enough at the junction of chorion and endometrium so that oxygen and nutrients can pass from the maternal blood to the fetal blood, and waste products in the opposite direction.
  • The placental membrane controls the transfer of a wide range of substances by several processes.


  • Simple diffusion: The movement of molecules from an area of high concentration to an area of low
  • Most molecules of physiologic importance are transferred by some active transport, thus they can be “Pumped” against a concentration gradient allowing the embryo to accumulate higher concentrations of nutrients that exist in the maternal


Group Physiologic role Substances Exchange mechanism
I Maintenance of biochemical homeostasis or protection against

sudden fetal death

Electrolytes, water and respiratory gases Rapid diffusion
II Fetal nutrition Amino acid, sugars and most

water soluble vitamins

Predominantly by active

transport system

III Modification of fetal growth or the

maintenance of pregnancy

Hormones Slow diffusion
IV Immunologic or toxic importance Drugs, anaesthetics, plasma proteins, antibodies and whole cells Rapid diffusion Pinocytosis or leakage through pores in placental




There many similarities between gases exchange across the placenta and the lungs.

  • The major difference, however, is that in the placenta it is a fluid to fluid system whereas, in the lungs it is a gas to fluid system.
  • The process of transfer of O2 from maternal to fetal blood involves its dissociation from the maternal blood, its diffusion through the placental membrane and finally its combination with fetal
  • The umbilical arteries carry deoxygenated blood from the fetus to the placenta, while the umbilical veins carry oxygenated blood from the placenta to the


  • The gas exchange in the placenta takes place through four basic systems.
    • Concurrent
    • Counter current
    • Multivillous
    • Pool
  • The efficiency of oxygen exchange varies with the particular system. It is greatest in the counter current system and least in the concurrent system. The efficiency of the multivillous system is intermediate between the above mentioned systems. In the pool system, gas exchange is less than in the multivillous system but is comparable to a concurrent
  • It is difficult to ascertain which of these systems is primarily involved in a particular species and probably some species may contain more than one


  • The oxygenated blood from the dam is carried to the fetus through the tributaries of umbilical veins whereas the tributaries of umbilical artery carry the deoxygenated blood from the
  • Water moves very freely between the dam and
  • Of the total substances absorbed by the fetus 77% is
  • However, the water moves from the dam to fetus against the osmotic gradient and low concentration of plasma


  • Sodium is much restricted in the passage through placenta. Iron content is much higher in fetus, which is stored in liver, spleen and bone
  • The transfer of trace elements like copper is readily affected. This element also accumulates in the
  • Calcium and phosphorus enter the fetal blood against the concentration gradient. Depletion of calcium and phosphorus reserves from the dam occurs in cases of low plane of
  • Fetal blood comprises of 70–80% fructose whereas glucose predominates in maternal blood. Probably glucose is formed in the placenta and stored in the fetal liver which serves as a reserve energy
  • Placenta is not permeable to fat but the fatty acids and glycerol pass freely
  • Vitamin A, D and E are obstructed by placenta and hence their concentration in fetus is much lower. Since water soluble vitamins are synthesized in the rumen their concentration in fetus has not been


Placental Hormones

In addition to its role in transporting molecules between mother and fetus, the placenta is a major endocrine organ. It turns out that the placenta synthesizes a huge and diverse number of hormones and cytokines that have major influences on ovarian, uterine, mammary and fetal physiology, not to mention other endocrine systems of the mother.

This section focuses only on the major steroid and protein hormones produced by the placenta.


Steroid Hormones

Sex steroids are the best known examples of placental hormones. Two major groups are produced by all mammals:


Progestins: Progestins are molecules that bind to the progesterone receptor. Progesterone itself is often called the hormone of pregnancy because of the critical role it plays in supporting the endometrium and hence on survival of the conceptus.

The placenta of all mammals examined produce progestins, although the quantity varies significantly. In some species (women, horses, sheep, cats), sufficient progestin is secreted by the placenta that the ovaries or corpora lutea can be removed after establishment of the placenta and the


pregnancy will continue. In other animals (cattle, pigs, goats, dogs), luteal progesterone is necessary throughout gestation because the placenta does not produce sufficient amounts.

Progestins, including progesterone, have two major roles during pregnancy:

  • Support of the endometrium to provide an environment conducive to fetal survival. If the endometrium is deprived of progestins, the pregnancy will inevitably be terminated.
  • Suppression of contractility in uterine smooth muscle, which, if unchecked, would clearly be a disaster. This is often called the “progesterone block” on the myometrium. Toward the end of gestation, this myometrial-quieting effect is antagonized by rising levels of estrogens, thereby facilitating

Progesterone and other progestins also potently inhibit secretion of the pituitary gonadotropins luteinizing hormone and follicle stimulating hormone. This effect almost always prevents ovulation from occurring during pregnancy.


Estrogens: The placenta produces several distinct estrogens. In women, the major estrogen produced by the placenta is estradiol, and the equine placenta synthesizes a unique group of estrogens not seen in other animals. Depending on the species, placental estrogens are derived from either fetal androgens, placental progestins, or other steroid precursors.

With few exceptions, the concentration of estrogens in maternal blood rises to maximal toward the end of gestation. Two of the principle effects of placental estrogens are:

  • Stimulate growth of the myometrium and antagonize the myometrial-suppressing activity of progesterone. In many species, the high level of estrogen in late gestation induces myometrial oxytocin receptors, thereby preparing the uterus for
  • Stimulate mammary gland development. Estrogens are one in a battery of hormones necessary for both ductal and alveolar growth in the mammary

Like progestins, estrogens suppress gonadotropin secretion from the pituitary gland. In species like humans and horses, where placental estrogens are synthesized from androgens produced by the fetus, maternal estrogen levels are often a useful indicator of fetal well being.


Protein Hormones: Several protein and peptide hormones are synthesized in placenta of various species. They have effects on the mother’s endocrine system, fetal metabolism and preparation of the mother for postpartum support of her offspring.


Chorionic gonadotropins: As the name implies, these hormones have the effect of stimulating the gonads, similar to the pituitary gonadotropins. The only species known to produce a placental gonadotropin are primates and equines. The human hormone is called human chorionic gonadotropin or simply hCG. This hormone is produced by fetal trophoblast cells. It binds to the luteinizing hormone receptor on cells of the corpus luteum, which prevents luteal regression. Thus, hCG serves as the signal for maternal recognition of pregnancy. The first hormone you produced was hCG. Equine chorionic gonadotropin is also produced by fetal trophoblast cells. It is actually the same molecule as equine luteinizing hormone.


Placental lactogen: These hormones are molecular relatives of prolactin and growth hormone. These hormones have been identified in primates, ruminants and rodents, but not in other species.



Relaxin: Relaxin is a hormone thought to act synergistically with progesterone to maintain pregnancy. It also causes relaxation of pelvic ligaments at the end of gestation and may therefore aid in parturition. In some of the species in which relaxin is known to be produced, it is produced by the placenta, while in others, the major source is the corpus luteum. In some species, relaxin is produced by both the corpus luteum and placenta.



Bovine : Applied clinical anatomy and embryology of female reproductive tract – Hereditary and congenital
anomalies of female reproductive tract –Puberty and sexual maturity and their endocrine control- Delayed
puberty- Its causes, clinical approach, treatment and prevention of delayed puberty- Applied reproductive
physiology and endocrinology of oestrous cycle- Oestrous cycle and factors affecting the length of the oestrous cycle-Aberrations of oestrus and their clinical management and problems in oestrus detection
and oestrus detection aids –Transportation and survivability of gametes in female reproductive tractFollicular Dynamics and its clinical impact on fertility improvement- ovulation and aberrations of
ovulation-Incidence causes, diagnosis treatment and prevention of ovulatory failures- Fertilization and
aberrations of fertilization- Fertilization failures – embryonic mortality-incidence, causes, diagnosis,
treatment and prevention – Pathological affections of ovary, uterine tubes, uterus, cervix , vagina and
external genitalia – Clinical management of specific and non-specific forms of infectious infertilityRole of nutrition, climate and stress on reproductive efficiency – Managemental causes of infertilityAnoestrus and repeat breeding syndrome – Diagnostic procedures in infertility investigation – Clinical
uses of hormones and drugs in the management of infertility- Surgical procedures for correction of
abnormalities of the female reproductive tract. Herd reproductive health management and fertility
parameters in individual animals and in herds. Assisted reproductive techniques: Synchronization of
estrus and ovulation and its principle. methodology and implications- Multiple ovulation and Embryo
transfer technology-In vitro fertilization. Equines: oestrous cycle- Seasonality- breeding managementAberrations of oestrous cycle and ovulations- Techniques of Pregnancy diagnosis- Clinical management
of specific and non-specific forms of infectious infertility- Diagnostic procedures in infertility
investigation Ovines and caprines: oestrous cycle- Seasonality- Control of oestrous cycle and infertility
Swines : oestrous cycle- breeding management- Techniques of Pregnancy diagnosis and infertility Canines
and Felines : oestrous cycle- breeding management- Phantom pregnancy- Medical termination of pregnancy
– Aberrations of oestrous cycle- Medical and surgical management of affections of ovary, uterine
tubes, uterus, cervix, vagina and external genitalia – Methods of Population control by medical and
surgical techniques. Comparative reproductive events in camel Principle, procedure and application of
ultrasonography in farm and pet animal reproduction
Farm and pet animals – Maternal recognition of pregnancy – Applied Endocrinology of pregnancy –
Pregnancy diagnosis- Duration of pregnancy -Factors affecting gestation length- Care and
management of pregnant animals- Implantation, Placentation- Classification, functions –Wandering of
ovum- Telegony- Superfetation and Superfecundation – Clinical management of specific and non specific
causes of abortion, extra uterine pregnancy, dropsy of fetal membranes and fetus, mummification,
maceration, cervicovaginal prolapse, uterine torsion and hysterocele. Parturition- Signs of approaching
parturition – Stages of parturition – Initiation and induction of parturition – lactational disorders –
Puerparium and factors affecting puerparium – Postpartum care of the dam and neonate in different species of
farm and pet animals – Dystocia – Classification – Clinical signs and diagnosis – Handling of
Fetal and maternal dystocia – Obstetrical interventions – Mutation – Forced extraction – Fetotomy –
Cesarean section in small and large animals – Maternal obstetrical paralysis – Retention of fetal membranes,
Total uterine prolapse and common metabolic diseases of puerperal period – Post partum hemorrhage –
Sub involution of placental sites – Injuries incidental to parturition – Post partum uterine infections –
Post partum resumption of ovarian activity . UNIT–3 (VETERINARY ANDROLOGY AND A.I.)
Farm and pet animals – Comparative clinical reproductive anatomy and endocrinology of the male
reproduction – Common congenital and genetic defects of the male reproductive tract – Puberty and
sexual maturity and factors affecting them – Sexual behaviour and libido – Sperm transport, erection
and ejaculation – Coital injuries and vices in male animals – Semen and ejaculate – Semen
collection techniques- Structure of Spermatozoa – Semen evaluation – Semen extenders, dilution,
preservation and post thaw evaluation – Artificial insemination techniques in farm and pet animals –
Forms of male infertility – Impotentia coeundi and impotentia generandi – Affections of the scrotum,
testis, accessory sex glands, penis and prepuce – Breeding soundness evaluation of bull – In vitro tests for
evaluation of male fertility – Medical and surgical techniques for population control of the male reproduction
– Surgical procedure on the male reproductive tract in farm and pet animals.




Learning objectives 

  • This module deals with
    • Hemoglobin and its properties
    • Types of hemoglobin
    • Regulation and concentration of hemoglobin
  • Hemoglobin is the iron-containing oxygen-transport metalloprotein present in the red blood cells of all vertebrates that carries oxygen from the lungs to the tissues and carbon dioxide from the tissues back to the
  • The oxygen carrying capacity of hemoglobin is 60% more than that of
  • It also functions as a buffer in the regulation of acid base
  • A hemoglobin molecule is a complex substance consisting of conjugate protein composed of a pigment heme and a protein,
  • The protein portion of each of these chains is called “globin”. The a and b globin chains are very similar in structure. In this case, α and ß refer to the two types of
  • The globin is a conjugated protein and heme contains iron in ferrous
  • Hemoglobin contains four polypeptide chains namely two alpha and two beta Each of the four chains unites with a heme group resulting in a hemoglobin molecule.
  • ?


  • Hemoglobin (Hb) is synthesized in a complex series of steps.
  • The heme part is synthesized in a series of steps in the mitochondria and the cytosol of immature red blood cells, while the globin protein parts are synthesized by ribosomes in the cytosol.
  • Production of Hb continues in the cell throughout its early development from the proerythroblast to the reticulocyte in the bone marrow. At this point, the nucleus is lost in mammalian red blood cells, but not in birds and many other Even after the loss of the nucleus in mammals, residual ribosomal RNA allows further synthesis of Hb until the reticulocyte loses its RNA soon after entering the vasculature.

Heme synthesis 

  • Heme is synthesized in a complex series of steps involving enzymes in the mitochondrion and in the cytosol of the cell. The first step in heme synthesis takes place in the mitochondrion, with the condensation of succinyl CoA and glycine to form delta-amino levulinate. This molecule is transported to the cytosol where a series of reactions produce a ring structure called protoporphyrin
  • Many enzymes concerned with heme synthesis are intra-mitochondrial, limited to erythroid precursors including
  • The ALA synthetase is the rate-limiting enzyme of the Hb synthesis, present within the mitochondria.

Globin synthesis 

  • After heme is synthesized within the mitochondria, 4 heme molecules combine with 4 globin polypeptides to form one molecule of
  • The globin molecule of haemoglobin differs among the species, whereas there is no difference in the heme portion.
  • The amount of Hb in the blood is influenced by age, sex, muscular activity, season, excitement Erythropoietin stimulates RNA and DNA synthesis, the cell division, heme synthesis and hemoglobin production.
  • At an oxygen pressure (PO2) of 100 mm of Hg in the lung, the Hb forms loose andreversible combination with oxygen, the oxyhemoglobin, but at low oxygen pressure of 40 mm of Hg at tissue level, it readily releases oxygen to the tissues for complex metabolic process.
Species Hb (g/dl)
Dog 12-18 (15)
Cat 8-15 (12)
Cow 8-15 (11)
Sheep 8-16 (12)
Goat 8-14 (11)
Horse 11-19 (15)
Pig 10-16 (13)
  • Based on physiological functions, the hemoglobins are typed as adult hemoglobin and fetal hemoglobins. Electrophoretically, the Hbs are classified as HbA, HbB, HbC and HbF. Human beings show three types of Hb, HbA (98%), HbA2 (2%) in the adult and HbF in fetus and new born. HbA has 2 µ -chains and 2 ß -chains; HbA2 is represented by 2 µ and 2 delta – chains. HbF has 2 µ -chains and 2 γ -chains.
  • In adult sheep HbA (2 µ, 2 ß) is electrophoretically fast and has higher O2 affinity than HbB with 4γ chains. Sheep having HbA or HbB under anemia or hypoxic condition develop another type of Hb, the HbC, which partially or completely replaces the Such a change is also observed in goat. HbC is the naturally occurring Hb in sheep during growth period. HbF has higher affinity for O2. In many animal species fetal hemoglobin (HbF) is replaced by the adult types within 4 to 8 weeks after birth. In adult cat the HbA and HbB are found in the same erythrocyte.
  • Some of the Hb variants, HbS, HbC, HbE are associated with specific hematologic disorders. HbS is responsible for sickle-cell anaemia in Negro race. HbC and HbE cause failure of synthesis of alpha or beta chains thus results in alpha or beta thalassemia.



  • Hemoglobin has an important physiological relationship with Oxygen forms loose and reversible combination with hemoglobin called oxyhemoglobin when the erythrocytes passes through the pulmonary capillaries. Since there are four ferrous atoms in the hemoglobin molecule, four molecules of oxygen are transported by a molecule of hemoglobin.
  • ?
  • As blood is transported through the systemic capillaries hemoglobin loses its oxygen to the tissues and becomes hemoglobin Hemoglobin shows progressive increase in the affinity for O2 after the first two molecules of O2 are taken up by the heme.
  • The oxygen carrying capacity of the hemoglobin is dependent on the pigment it contains

which in turn depends on the iron content for oxygen combining capacity.

  • The amount of iron present in the blood is minute about 0.334% of the hemoglobin molecule or 04 to 0.05% of the blood itself. Each gram of Hb combines with a maximum of 1.34 ml of oxygen.
  • In the lung (PO2 100 mm Hg) the oxygen binds with Hb which shows 97% saturation. Onehundred ml of blood containing approximately 15 grams of Hb, can carry approximately

19.4 ml of oxygen.

  • In the tissue capillaries, (PO2 40 mm Hg) Hb is 72% saturated and contains 14 ml ofoxygen per 100 ml of blood, which indicates oxygen release from the Hb into the tissues. Thus under normal resting conditions about 5 ml of oxygen is transported by each 100 ml of blood during each cycle to the tissues. During heavy exercise this is increased to about 15 times normal. The oxygen hemoglobin dissociation curve is “S” shaped or sigmoid shaped.


Myoglobin (Muscle hemoglobin)


  • It is a true hemoglobin and functions to store oxygen in the muscle. It contains only one heme and a polypeptide chain. It contains only one iron atom and can therefore store only one molecule of O2.
  • Its molecular weight is approximately 17,000, which is four times less than Hence it

can pass through glomerulus.

  • The oxygen dissociation curve with myoglobin is hyperbolic (very steep). The appearance of myoglobin in the urine is referred to as myoglobinuria or azoturia, which is a very characteristic symptom of monday morning sickness in


Carboxyhemoglobin (HbCO)


  • Hb has 200 times more affinity for carbon monoxide than


Hb+ CO ® HbCO


  • Carbon monoxide firmly attaches with the Fe++ molecules of heme, thus interferes with the transport of O2 as oxy 0.1% of CO in inspired air will convert 20% of Hb into HbCOwithin 30 to 60 minutes.
  • Oxygen under higher partial pressure is the only means to reverse the




Methemoglobin (ferrihemoglobin)


  • It is formed by the oxidation of ferrous iron to ferric iron. During the circulation of blood about 1% of methemoglobin is formed by the oxidation of ferrous iron to ferric iron. Ferrihemoglobin cannot combine with oxygen, hence is useless as a respiratory pigment in the blood. It produces dark colored blood. Glutathione (GSH) in the erythrocytes prevents the excessive oxidation of ferrous iron into ferric
  • Chemicals like nitrates, sulphanamides, aminophenol and acetanilide cause increased concentration of methemoglobin in the blood. Horse blood at normal conditions shows significant amounts of methemoglobin. The normal blood of dog and cat has about 1% of methemoglobin.


  • When white light is passed through a solution of hemoglobin or one of its derivatives, certain wavelengths are The resulting spectrum is termed as absorption spectra; the region of absorption is known as absorption bands.
  • They can be seen by examining the solution with a
  • When white light is examined spectroscopically, a series of colours known as spectrum (VIBGYOR) is
  • When sun light is examined, certain black vertical lines called as Fraunhofer’s lines are found at definite places in the spectrum; these lines are designated as A, B, C, D, E, etc. In lamp light, these lines are not
  • When hemoglobin solution or its derivatives are examined in certain concentrations spectroscopically, absorption bands of definite size, appearance, and position are
  • Hence, spectroscopic examination helps to identify these pigments in solution. E.g. Dilute oxy-Hb solution shows two absorption bands between line D and E; adding a reducing agent (produces reduced-Hb) gives one band at line
  • Carboxy-Hb shows two bands but adding a reducing agent does not produce a single
  • Met-Hb shows a band between line C and



Learning objectives


  • This module deals with
    • production of leukocytes
    • types of leukocytes
    • fate and concentration of leukocytes


  • The process of formation of leukocytes is known as Leukopoiesis. Leukocytes are produced from the pleuripotent stem










  • Leukocytes are large sized, nucleated cells, lesser in number and do not have hemoglobin content. These cells show polymorphic forms, which differ morphologically and functionally.
  • Majority of the WBCs is larger than RBCs; while RBCs are present in millions per ml of blood, the WBCs are present in thousands per ml of
  • The ratio of WBC to RBC varies from 1:100 in chicks to 1:1300 in goats, 1:600 in dog and cat, 1:800 in cattle 1:1000 in horse 1:1200 in sheep and 1:700 in


Types of leukocytes


  • Based on the staining nature of the cytoplasmic granules when subjected to Leishman’s stain, leukocytes are classified as granulocyteswhich are further classified into three groups the neutrophils, eosinophils and
  • Some of the leukocytes have cytoplasmic granules but they are non-visible even after staining with Leishman’s stain, hence they are known as agranulocytes. The lymphocytes and monocytes form two groups of this




Site of production of WBCs


  • The granulocytes and the megakaryocytes are produced from the myelocytes of the bone marrow hence often referred as myeloid series of blood
  • The lymphocytes and the plasma cells are formed from the lymphoid tissues such as lymph nodes, spleen and lymphoid tissues of the bone marrow, gut
  • The monocytes are produced by the mononuclear phagocytic system (MPS) cells of spleen and bone marrow (reticuloendothelial system cells).


  • Neutrophils are produced in the bone marrow from the extravascular neutrophilic myelocytes. They are numerously found in the blood of most
  • The nucleus of mature cells is divided into lobes, usually five lobes and are stained blue or purple by Leishman’s stain. They have abundant and fine granular cytoplasm which take up the neutral
  • These granules store lysosomes, which contfain hydrolytic enzymes, proteolytic enzymes and lipases to digest the invading
  • The oxidative enzymes of the lysosome produce hydrogen peroxide, which attack the bacterial cell wall to cause bactericidal
  • Neutrophils are highly motile, responds to chemotaxis and actively phagocytic, thus serve as a first line of defence against invading organisms, (bacteria, viruses and cellular remnants).
  • At the onset of infection neutrophils produce pyrogens which act on thermo-regulator centre of the brain results in fever. This rise in body temperature slows the reproduction process of bacteria and viruses
  • Immature forms of neutrophils are characterized by unsegmented or less number of nuclear lobes  and  are  referred  to  as  juvenile  or  band    Pseudo  neutrophils   and heterophils are comparable to neutrophils, which are present in rabbit and poultry respectively.
  • Heterophils contain large rod or spindle shaped granules, which are acid in reaction and stain red or pink with eosin.






  • It indicates more number of neutrophils in the circulation.
  • Physiological neutrophilia occur in conditions like exercise, emotion, pregnancy, lactation and
  • Abnormal or pathological neutrophilia may be due to acute inflammation following injury, surgery, burns, arthritis and acute infection by pyrogenic bacteria.
  • Shift to left is a term used to describe an increase in the number of immature neutrophils (Band cells) in the circulation which is characteristic of bacterial infections. The shift to left is clinically helpful in diagnosis of traumatic reticulopericarditis (TRP).






  • It indicates reduction in neutrophils in the circulation, which is very common in viral infections and chronic infections like TB, brucellosis and protozoal and fungal
  • Injection of antiinflammatory drugs (cortisol) and antibacterial drugs (chloramphenicol and sulphanamides) may result in




  • They are large cells which contain large cytoplasmic granules that stain red or purple eosin stain. They have bilobed nucleus, connected by a thin
  • The cytoplasmic granules contain enzymes, which are rich in oxidases‚ and peroxidases. Eosinophils are produced from the bone marrow and are highly motile, but less phagocytic.
  • Eosinophils function to detoxify the proteins of the parasites, phagocytise antigen- antibody complexes, the inflammatory products of the mast cells and
  • These cells have antiheparin‚ and anti- histaminic substances, thus act as an anti- inflammatory and anti- allergic agent. Eosinophils release profibrinolysin‚ which is then activated to fibrinolysin‚ and causes the dissolution of old blood




  • Eosinophilia: It is increased number of eosinophils in the circulation. This condition is common in G.I. parasitic infections, allergic disorders like bronchial asthma, allergic rhinitis, in skin diseases like eczema and dermatitis, drug reactions following penicillin and sulphanamides
  • Eosinopenia: It is decreased number of eosinophils in circulation. This condition occurs following stress , administration of ACTH or cortisol




  • These cells are found in the blood in lower concentration. They have irregular shaped nucleus and the granules are stained blue by the basic dye of Leishman’s stain. They originate in the bone marrow and have slight or no
  • Extravascularly, basophils enlarge and become tissue mast cells. Both basophils and mast cells release heparin (anticoagulant)‚ and vasodilator substances histamine, serotonin and bradykinins. Thesevasodilators causes increased blood flow and reddish colour (hyperemia) at the site of infection followed by increased permeability of the plasma and proteins from the blood vessels, a process calledinflammation. Basophils and mast cells have receptors for immunoglobin






  • Basophilia: It is increase in basophils, and it is seen in allergic conditions and hematological


  • These cells are characterised by well defined centrally placed nucleus, surrounded by cytoplasm. According to the size and the ratio of nucleus to cytoplasm, these cells are further divided into 3
    • Small lymphocytes: These are small sized cells with a large notched
    • Medium lymphocytes: These are medium sized, which have notched nucleus surrounded by thin rim of
    • Large lymphocytes: These have comparatively small sized nucleus with broad rim of
  • Lymphocytes are actively motile cells with amoeboid movement and are mainly concerned with the development of immunity against specific disease organisms. They have no phagocytic




  • Lymphocytosis: This condition indicates increased number of lymphocytes in the circulation, which is common in viral infection (eg) infectious
  • Lymphopenia: This condition indicates decreased number of lymphocytes in circulation and is seen in cases of TB, acute stress and glucocorticoid injection.


  • These are the largest of WBCs, characterised by kidney or bean shaped
  • Monocytes are actively motile, pinocytic and also highly phagocytic, which may migrate into the tissue spaces and become macrophages. These cells are much more powerful phagocytes than neutrophils by their ability to engulf much large sized particles, necrotic tissues and more number of
  • Monocytes leave the blood and are attracted to the tissues by chemotaxis and lymphokines and they become macrophages, example reticular cells of lymph nodes, spleen, bone marrow and Kupffer cells of the liver






  • This condition indicates increased number of monocytes in the circulation and is seen in hematological malignancies, endocarditis, typhoid, TB, brucellosis and prolonged blood parasitic infections. Eg:









Total leukocytes (x103/  

Differential Leukocyte Count (%)









Band Mature




0-3(0.8) 60-77


12-30 (20) 3-10 (5) 2-10 (4) Rare




0-3 (0.5) 35-75


20-55 (32) 1-4 (3) 2-12 (5) Rare


4-12 (8) 0-2




45-75 (58) 2-7 (4) 2-20 (9) 0-2 (0.5)


4-12 (8) Rare 10-50


40-75 (62) 0-6 (2.5) 0-10 (5) 0-3 (0.5)


4-13 (9) Rare 30-48


50-70 (56) 0-4 (2.5) 1-8 (5) 0-1 (0.5)


5.5-12.5 (9) 0-2




25-70 (44) 1-7 (4) 0-11 (4) 0-3 (0.5)


11-22 (16) 0-4 (1) 28-47


39-82 (53) 2-10 (5) 1-11 (3) 0-2 (0.5)
Chicken 20-30 25-30 55-60 10 3-8 1-4




  1. It is very difficult to assess the life span of leukocytes because the WBCs move between blood and
  2. The life span of granulocytes is normally 9 days but once they are released into circulation from bone marrow their life span is 4 to 8
  3. During infection, the life span in “B” lymphocytes live for 3-4 days only but “T” lymphocytes may live for 1-3 years in tissues and return to circulation many times.
  4. The monocytes also have short transit time in the blood (24 hours) before migrating to the tissues where they become tissue macrophages and can live for months or even


  • Leukocytosis:
    • It is an increase in the number of leukocytes which is an indication of presence of some



  • Leukocytosis may be physiological (related to time of day, meal, exercise, epinephrine, stress) or pathological. Bacterial infection shows leukocytosis with neutrophilia, whereas viral infections result in
  • Leukemia:
    • Pathologically, cancer of leukocyte producing tissues results in abnormally high white cell count which is known as


  • Plasma cells are white blood cells which produce large volumes of
  • They are transported by the blood plasma and the lymphatic system and originate from the bone marrow.
  • They are otherwise known as plasma B cells , plasmocytes , and effector B cells .
  • They are present in lymph nodes ,spleen and diffuse lymphoid tissue of alimentary and respiratory


  • Plasma cells are large lymphocytes round in shape containing a granular cytoplasm which stains with basic
  • The nucleus is eccentric in position and typically represents clumps of chromatin in a radiating manner, resembling a “cart -wheel” or clock face in
  • They have a considerable nucleus-to-cytoplasm
  • The cytoplasm contains a conspicuous Golgi apparatus and abundant endoplasmic reticulum .
  • Immunoglobulins are localised in the endoplasmic reticulum where it sometimes forms aggregates called as Russel


  • When specific B-lymphocytes are stimulated by specific antigen, they enlarge and become lymphoblast, some of which further differentiate to immature plasmablasts which finally forms, the plasma


  • These cells are rarely seen in the circulation, which are formed by the lymphoid tissues (spleen).
  • They play a very important function in body defence
  • They are involved in the production of humoral
  • Plasma cells are concerned with the synthesis, storage and release of immunoglobulins at a very rapid
  • A plasma cell can only synthesize an antibody of a single specimen, either IgM or IgG or IgA except in primary immune response when a plasma cell producing IgM initially, may later switch over to the synthesis of IgG
  • Mature plasma cells are end cells and survive only a few weeks and die after a few cell division.





Learning objectives

 This module deals with

    • Functions and composition of erythrocytes
    • Shape, structure and size of erythrocytes
  • Transport hemoglobin which in turn carries oxygen from the lungs to the
  • RBCs contain large quantity of carbonic anhydrase which catalyzes the reversible reaction between carbon dioxide and water. Thereby makes it possible for the water of the blood to transport enormous quantities of carbon dioxide from the tissues to the lungs in the form of
  • Hemoglobin in the cells is an excellent acid base buffer. Therefore, the RBCs are responsible for most of the acid base buffering power of whole blood
  • The mammalian RBCs are usually non-nucleated and non-motile cells, biconcave circular disc with central pale spot. Its shape differs in various species of animals:
    • Dog, Cow, Sheep: Markedly biconcave.
    • Horse and cat: Shallow concaving,
    • Goat: Very shallow or flat surfaced
    • Camel and Deer: Elliptical and sickle
    • Cold blooded animals (amphibians and birds): Elliptical and


Significance of biconcavity of RBCs


  • It increase the surface area thus facilitating the exchange of oxygen and carbon dioxide carried by the
  • The cell membrane of RBC is made up of lipids (lecithin, cephalin and cholesterol) and glycoprotein encloses a spongy inner structure called the stroma.
  • The RBC membrane protein, Spectrin forms the inner lining of the membrane, whereas the outer layer is formed by glycoproteins, have the blood group antigens. The cell membrane is highly permeable to lipid soluble substances, glucose, urea and
  • Hemoglobin is deposited in the inter-spaces of the spongy stroma. The surface of mature erythrocyte is smooth, while the immature RBCs have relatively rough
  • Average diameter of RBC ranges from 4.1 to 7.5 µm .


Species Size (µm )
Goat 4.1
Sheep 5.0
Cattle 5.6
Horse 5.6
Pig 6.2
Cat 6.5
Dog 7.3
Man 7.5


  • Surface area‚ varies from 57-67m2/ kg body weight in It is lowest in goat (lesser diameter) and highest in man (greater diameters).
  • Erythrocyte contains 62 – 72% water and 35% solids. Of the solids, 95% is contributed by Hb and the remaining 5% by cell and stromal protein, lipids, phospholipids, cholesterol, cholesterol esters, neutral fat and

Energy is required for RBCs to


  • To maintain the shape and flexibility of the cell
  • To preserve high K+, low Na+ and low Ca++ ions within the RBCs against the concentration gradient of these ions of
  • To maintain iron in ferrous (Fe++) state (to reduce ferric to ferrous state, NADH and NADPH are required).
  • To generate reduced glutathione (anti-oxidant); this helps to maintain the ferrous



  • To generate 2,3 Diphospho glycerate (DPG) for O2
  • Mitochondria are absent in mature erythrocytes. These cells derive their energy from glucose metabolism via anaerobic Embden- Meyerhoff (EM) pathway (90%) and oxidative pentose cycle (10%) which produce NADH and Kreb’s cycle is very much reduced in activity.
  • The concentration of RBC depends on various factors such as interspecies, intraspecies and diurnal variation, age, sex, environment, exercise, nutritional status, climate and altitude.

Concentration of RBC in domestic animals (millions/ mm3 of blood)


Species Concentration of RBC
Fowl 3.0 (2.8 – 3.2 )
Pig 6.5 (5.8- 8.0)
Dog 6.8 (5.5-8.5)
Sheep 12.0 (8.0-16.0)
Cattle 7.0 (5.0-10.0)
Goat 13.0 (8.0-18.0)
Horse 6.5 (6.5-12.5)
Cat 7.5 (5.0-10.0)
Man 5.4 (5.0-6.0)
Women 4.8 (4.0-5.0)


Learning objectives 

  • This module deals with
    • Abnormalities of RBC concentration
    • Erythrocyte indices
  1. Polcythemia
  2. Oligocythemia
  3. Anaemia


  • It is otherwise known as It is a condition of increased number of RBCs in the circulation. It is of two types.
    • Physiological (secondary) polycythemia
  • An increase in RBCs occurs as a compensatory measure (in high altitude of 14000 to 17000 feet to compensate low PO2). Whenever tissues becomehypoxic because of too little oxygen in the atmosphere, for example at high altitude or because of failure of delivery of oxygen in the tissues as in cardiac failure, then the blood forming organs automatically produce large quantities of extra RBCs i.e 30% above the
  • Increased Hb requirement during heavy muscular exercise to meet increased oxygen demand. In sports animals (racehorse, hunting dogs) RBC elevation is a normal
  • Increased environmental stress / temperature, the spleenic contraction, and increased RBC synthesis by the bone marrow cause increased number of RBCs into the
  • Hemoconcentration due to water loss that occurs in vomiting, diarrhoea, prolonged high fever and burns also causes
  • Pathological polycythemia
    • Due to decreased O2 supply to the tissue, chronic carbon monoxidepoisoning, myeloid (bone marrow) cancer, pulmonary emphysema, repeated
    • Polycythemia vera is the condition due to bone marrow cancer (myeloid leukemia). It occurs as a result of genetic aberration in the hemocytoblastic cell line that produces the blood cells.


  • Reduction in the number of erythrocytes in the circulation is called as oligocythemia
  • Physiological oligocythemia occurs due to hemodilution; RBC number per unit volume is reduced. Example: pregnancy.
  • Pathological oligocythemia is also known as anaemia.


  • Abnormal reduction in the number of the erythrocytes or the hemoglobin content in the blood or both.



  • Excessive whole blood loss occurs in hemorrhage or by blood sucking parasites (Hookworms, ticks), increased destruction of RBCs by the reticuloendothelial
  • Impaired RBC production and Hb synthesis, due to deficiency of Fe, Cu, Vitamin B12 and folic
  • Hemolytic:
    • Disease caused by blood parasites, (babesiosis) or drugs like sulphanamides, antimalarial drugs and high doses of aspirin (analgesic)


Anemia due to defective blood formation:

  • Aplastic anemia
    • It occurs due to lack of functional bone marrow caused by excessive x-ray treatment or bone marrow cancer, certain industrial chemicals, drugs etc.
  • Anemic anemia
    • Megaloblastic anemia:
      • It is due to deficiency of iron, folic acid, Vitamin B12 (extrinsic factor) andintrinsic factor of the gastric
    • Microcytic and hypochromic anemia:
      • It results due to deficiency of iron results in small sized, decreased number of RBCs and low Hb
    • Macrocytic and hyperchromic anemia:
      • Lack of extrinsic factor, the Vitamin B12 causes decreased number of RBCs,large sized RBCs and high Hb content because the erythroblasts cannot proliferate rapidly enough to form normal number of RBCs, the cells that are formed are mostly oversized, bizarre in shape and have a fragile membrane.
    • Pernicious anemia:
      • It occurs due to the deficiency of the intrinsic factor of the gastric mucosa that interferes with the Vitamin B12


Anemia due to excessive blood loss or increased RBC destruction:

 Hemorrhagic anemia:

    • Excessive blood loss due to accident, peptic ulcers
  • Hemolytic anemia:
    • Following acute destruction of RBCs (haemolysis) the number of RBCs is below normal, but the RBC size and Hb content are normal, known as normocytic and normochromic anemia.


  • Blood parasites: babesiosis, theileriosis and trypanosomiasis;
  • Chemicals: Copper, lead, nitrate and nitrite.

Anemia due to abnormal structure of RBC: 

  • In some hereditary diseases the defects are with the RBC membrane – e.g., sickle cell anemia, defects in the globin chain structure (thalassemia) or its synthesis or the deficiency of the enzymes of the RBCs energy system, the pyruvate kinase and glucose 6 phosphate dehydrogenase (G.6-PD).
    • Sickle cell anemia:
      • In this type of anemia the cells contain an abnormal type of hemoglobin called as Hb “S”. It is caused by abnormal composition of β chains of the hemoglobin.
      • When this type of hemoglobin is exposed to low concentration of oxygen it precipitates into long crystals inside the erythrocytes. These crystals elongate the cell and it gives the appearance of sickle
      • The precipitated hemoglobin also damages the cell membrane so that the cells become highly fragile leading to
    • Thalassemia:
      • It is otherwise known as Cooley’s anemia or Mediterranean anemia. It occurs due to defect in the synthesis of α or β peptide chains to form hemoglobin or due to deficiency of enzymes of the RBC energy system, pyruvate kinase and G-6-PD thereby depressing the hemoglobin synthesis.


  • These indices help in the diagnosis various types of anemia (microcytic vs. macrocytic or normocytic).
  • Mean Corpuscular Volume (MCV):
    • It expresses the average cell size of the erythrocyte.
    • ?


  • Mean Corpuscular Hemoglobin (MCH):
    • It gives the average weight of Hb present in the
    • ?


  • Mean Corpuscular Hemoglobin Concentration (MCHC):
    • It is the average percentage of the mean corpuscular volume that the Hb occupies.
    • ?


Species MCV (fl) MCHC (%) MCH (pg)
Dog 60-77 (70) 32-36 (34) 20-24
Cat 39-55 (45) 30-36 (33) 13-17
Cow 40-60 (52) 30-36 (33) 19
Sheep 23-48 (33) 31-38 (33) 10-14
Goat 15-30 (23) 35-42 (38) 8
Horse 34-58 (46) 31-37 (35) 18
Pig 50-68 (63) 30-34 (32) 16-20




Learning objectives


  • This module deals with lifespan and fate of erythrocytes.



  • Life span of erythrocytes (days)
Cattle Sheep Goat Horse Dog Cat Pig Poultry

















  • In most of the domestic animals bone marrow functions as a chief site of destruction of erythrocytes, whereas in man it is the
  • In the birds liver acts as an organ of destruction of erythrocytes.


  • The erythrocytes have a remarkable capacity to change their shape when they pass through the capillaries but they become less deformable when they reach the end of their life
  • Two types of destruction of erythrocytes takes place,
    1. Intravascular hemolysis
    2. Extravascular hemolysis



  • About 10% of aged RBCs undergo intravascular hemolysis within the capillaries due to loss of compressibility of RBCs caused by increased membrane permeability and osmotic change.
  • When this occurs the hemoglobin is released, which combine with haptoglobulin which is removed by the cells of the mononuclear phagocytic system (MPS).


  • About 90% of the aged RBCs are directly destroyed by the mononuclear phagocytic system (MPS).
  • The Hb and proteins are catabolised by the MPS cells. The MPS (also known as reticulo- endothelial system) includes the histiocyte or macrophages, stellate or Kupffer cells of the sinusoids of the liver, spleen, mononuclear cells of bone marrow and lymph
  • The globin of the Hb is degraded to amino acids and is reutilized. Iron removed from the heme is stored in the MPS cells in the form of ferritin or hemosiderin and utilised for the synthesis of hemoglobin or enters the plasma and combine with apotransferrin to form transferrin. The transferrin enters the bone marrow to produce more
  • The heme is converted to bile pigments, biliverdin (a green pigment) and then reduced to bilirubin (a yellow pigment). The free bilirubin enters the plasma, binds with albumin and transported to liver. In the liver bilirubin is conjugated with glucuronic acid, secreted in bile to enter intestine. Large intestinal bacteria reduce the bilirubin to urobilinogen, most of that are excreted in feces in the oxidised form of urobilin or stercobilin which impart colour to
  • Part of the urobilinogen is reabsorbed into the enterohepatic circulation and reexcreted in bile. Some of the urobilinogen in the plasma enters the kidneys to be excreted in urine as urobilin.
  • Globin protein portion of hemoglobin is broken down to amino acid and used in the formation of new hemoglobin or other


Hemolysis caused by external agents like


  • Blood parasites: Babesiosis, theileriosis, trypanosomiasis and
  • Chemicals: Copper, lead, nitrate and nitrite


Learning objectives 

  • This module deals with
    • Erythropoiesis
    • Regulation of erythropoiesis


  • It is the processes of formation of erythrocytes, leukocytes and platelets in the body. Formation of erythrocytes and leukocytes respectively are known as erythropoiesis and leukopoiesis.
  • During embryonic state the blood islands of pander of the yolk sac functions as a site of hematopoiesis. The mesenchymal cells of the liver, spleen, bone marrow and lymph glands are the hemopoietic organs in early fetal
  • The bone marrow is concerned with the production of erythrocytes, granulocytes and platelets during   postnatal   life,   whereas   the   lymphocytes   production   occurs   in the lymphoid tissues of lymph glands, Payer’s patches of intestine, spleen and
  • The lymphoid tissues of the bone marrow and also the spleen are the sites of production for monocytes. In ruminants, hemolymph nodes (hemal) functions as spleen. It takes part in the erythropoiesis during the foetal period, while granulopoiesis, is more prevalent in postnatal life.
  • The mesenchymal cells of the yolk sac produce primitive stem cells, which give rise to the pleuripotent stem cells (colony forming units – CFU). These stem cells give rise to five different blast cells, viz.
    • Proerythroblast to form RBC
    • Myeloblast to form neutrophils, eosinophils and basophils
    • Monoblast to form monocyte
    • Lymphoblast to form lymphocyte
    • Megakaryoblast to form platelets. Depending on the microenvironment, e., the location of the stem cells and the growth factors, the stem cells differentiate into progenitor cells of different blood cells (Committed Stem Cells-CSC). A CSC that produces erythrocytes is called colony-forming unit-erythrocyte (CFU-E). Similarly, CFU that produce granulocytes and monocytes are designated as CFU- GM.
  • The stem cells continue to divide throughout the life of the animal and a part of the cells remains as pleuripotent stem cells and retained in the bone marrow to maintain supply of stem
  • The pleuripotent stem cells differentiate to form the CSC. Several hemopoietic growth factors and differentiation factors stimulate the growth and differentiation of these stem cells into a particular progenitor
  • Cytokinins are the growth factors that regulate the formation of blood cells. Two cytokinins that stimulate red cell and WBC formation are the colony stimulating factors and interleukins. Erythropoietin increases erythrocyte precursor formation.
  • From stem cell, the formation of reticulocyte takes about 72 hours and conversion of reticulocyte to erythrocyte requires 48 hours. Thus RBC formation requires 5 days
  • Under appropriate stimulation, CFU-E progenitor cells produce proerythroblast. Hb synthesis begins in polychromatophil erythroblast and maximum synthesis occurs in orthochromatic
  • The metarubricyte ejects the nucleus to become the reticulocyte that contains some mitochondria, ribosomes and endoplasmic reticulum. In 1-2 days, they develop into erythrocytes and enter circulation.
  • ?
  • The level of oxygen in the tissue is the principle regulatory factor of erythropoietic activity of the bone marrow. The kidney cells, during hypoxia, releases erythrogenin (erythropoietin releasing factor) from the glomeruli, which in turn acts on erythropoietinogen, an µ2 globulin of plasma and converts it into free erythropoietin(hemopoietin). Kidney produces 90% of erythropoeitin and liver produces about 10%.
  • Erythropoietin as a hormone stimulates hemopoietic stem cells of bone marrow to produce the committed stem cells-proerythroblast, thus initiates erythropoiesis. It stimulates,
    • The proliferation of rubriblast by mitosis in the developing
    • Accelerates maturation of the rubricytic
    • Induces the release of reticulocytes into the circulation.


  1. Vitamin B12 and folic acid are essential for the maturation of erythrocytes. Vitamin B12 isrequired for DNA synthesis and folic acid for RNA synthesis. Macrocytic anemia is a very common in Vitamin B12 and folic acid
  2. Thiamine (B1), Pantothenic acid, Nicotinic acid, Vitamin E and pyridoxine (B6), riboflavin,biotin and ascorbic acid are essential for Deficiency of Vitamin

B6 causes microcytic hypochromic anaemia in pigs. Pantothenic acid deficiency results in deficiency of ALA synthatase in birds and animals. Normocytic anemia in swine and primates is due to Vitamin E deficiency.

  1. Minerals such as iron, copper and cobalt are essential for erythropoiesis. Iron acts as an integral part of Hb which is absolutely essential for Hb synthesis. Copper acts as a co-factor in ALA dehydrase in Hb synthesis. It is  part of the enzyme ferroxidase which is necessary for oxidation of ferrous iron to ferric form and is necessary for the incorporation of  iron  into  Hb.  Copper  deficiency  is  common  in  pigs,  which  may  interfere  with  Fe absorption  and  utilization.  In  ruminants  cobalt  plays  a  key  role  for  the  synthesis  of Vitamin B12 by the rumen bacteria which in turn is required for the normal production of erythrocytes.


  • A low percentage (1 to 3%) of erythrocytes in circulation has a network of bluish threads within the cell and is called
  • These cells are immature RBCs, which have entered into the circulation at times of need from blood forming
  • In some diseases or due to excessive loss of blood or destruction of RBCs, the reticulocytic number increases in circulation. These cells have less or no O2 carrying capacity.


Physiology 1


This module deals with

    • composition and functions of blood
    • properties of blood


  • Blood is a fluid connective tissue that flows all over the body in the vessels of the cardiovascular
  • Transportation
  • Transport oxygen from lungs to tissues and carbon dioxide from tissues to lungs
  • Transport nutrients from GI tract to liver and other cells
  • Transport hormones from endocrine glands to target cells
  • Transport waste products from cells to excretory organs
  • Regulation
  • Maintains homeostasis
  • Regulates pH / acid base balance
  • Regulates body temperature and water balance
  • Regulates osmotic pressure
  • Protection
  • Provides immunity
  • Blood is composed of fluid in which the cells and cell fragments are suspended. The fluid portion is known as the plasma‚ and the suspended cellular elements are the
    • Erythrocytes (RBCs)
    • Leukocytes (WBCs) and
    • Thrombocytes (platelets)
  • Plasma constitutes about 55 to 70% of the blood volume, while the cellular components account roughly about 30-45% of the total It performs numerous functions that are essential for life and health.
  • Specific gravity is the ratio of weight of a given volume of a fluid to the weight of the same volume of distilled water measured at 25°
  • Plasma protein concentration is largely responsible for the specific gravity of the plasma. The cellular elements called the corpuscles have higher specific gravity than the



Species Specific gravity
Goat 1.042 (1.036 – 1.051)
Pig 1.045 (1.035 – 1.055)
Dog 1.048 (1.045 – 1.052)
Cat 1.050 (1.045 – 1.057)
Sheep 1.051 (1.041 – 1.061)
Cattle 1.052 (1.046 – 1.061)
Horse 1.053 (1.046 – 1.059)


  • The copper sulphate drop falling method is commonly used for the assessment of specific gravity of blood and plasma. Various factors influence the specific gravity of the


Specific gravity is increased in the following conditions


  • Polycythemia: High altitude, polycythemia vera, newborns etc.
  • Severe dehydration: Excessive fluid loss such as in vomiting,
  • Hemoconcentration: Loss of plasma as in


Specific gravity is decreased in the following conditions


  • Pregnancy: Increase in plasma volume causes hemodilution.
  • Renal diseases: Loss of albumin, oedema
  • Hemodilution: Hypersecretion or prolonged treatment with
  • Starvation and malnutrition: Decrease in plasma
  • Intravenous fluid
  • Viscosity is influenced by concentration of RBCs and plasma proteins. Among plasma proteins, the viscosity is mainly contributed by the gamma globulins which provide the resistance to blood flow and helps the normal pumping activity of the
  • It is normally about five times greater than water. Viscosity of blood  is  determined using viscosimeter.
  • An increase in the viscosity of blood is seen in conditions like polycythemia, congestive heart failure, jaundice, vomiting, diarrhoea etc, whereas a decrease in the viscosity is commonly noticed in anemia, oedema
  • It is the fluid portion of the blood. It is yellow to colourless depending on the quantity, species of the animal and animal’s
  • The plasma colour is golden yellow in dog, colourless or slightly yellow in sheep and goat, while it is highly yellow coloured in horse and cow which is chiefly due to bilirubin‚ and to some extent by the carotene, xanthine and other pigments.


Icterus index


  • It is a measure of the yellow colour of the plasma. It is measured by comparing the colour of the plasma with a standard solution of potassium
  • Plasma is obtained by adding anticoagulant to whole blood to prevent clotting and centrifuging it for settling down of the


Composition of Plasma


  • Plasma is made up of water to the extent of 91 – 92%; Solids : 8 – 9%; the solid portion of plasma includes proteins: 6 – 8 g %: Organic and inorganic compounds: 2 – 3 %


Organic Carbohydrates : Glucose, Lactate, Pyruvate
Inorganic Macro level : Fe, Cl, SO4, PO4, Micro level : Mn, Co, Cu, Zn, Iodide.
Plasma proteins Albumin, Globulin, and Fibrinogen
Non Protein Nitrogenous (NPN)


Urea, Uric acid, Creatine, Creatinine, Salts of Ammonia
Lipids Neutral fat, Cholesterol, Phospholipids, Lecithin
Others Enzymes, Hormones, and Vitamins


  • In the absence of the anticoagulants, the blood comes out of the blood vessels and gets coagulated to form a blood clot. On shrinking it discharges a clear watery liquid called the serum.
  • Serum is also obtained by collecting the blood without the addition of anticoagulant and allowing it to clot. Later, upon shrinkage of the blood clot the serum is
  • It differs from the plasma in lacking fibrinogen, prothrombin and other coagulation factors which are involved in blood
  • The normal pH of the blood is 4.
  • The venous blood is slightly towards acidic side because of  the  increased content of  CO2, whereas the arterial blood is slightly more towards alkaline
  • The plasma is more alkaline than the
  • The blood pH range:

o     Dog    : 7.32- 7.68

o      Cattle : 7.35 – 7.50

o      Horse : 7.35 – 7.43

  • Fowl : 56.
  • Excessive production of metabolic acid products causes abnormal reduction in the alkaline reserve leading to the condition referred to as acidosis, whereas abnormal increase in the alkaline reserve is called as alkalosis.


Learning objectives 

  • This module deals with
    • types of plasma proteins
    • functions and normal concentration of plasma proteins
  • Plasma proteins contribute about 7% of the total organic molecules of the plasma. The major proteins present in plasma are:
    • Albumin (55%),
    • Globulins (38 %) and
    • Fibrinogen (7 %).
  • Liver functions as a chief site of synthesis of plasma proteins, albumin, fibrinogen, prothrombin and some of the While the gamma globulins are synthesised extra- hepatically in the lymph nodes and in the Mononuclear Phagocytic System (MPS) of spleen and bone marrow.
  • The ratio of albumin to globulin is 1:0.7. There are species variations in the ratio of plasma proteins e. albumin: globulin ratio. In humans, sheep, goats and dogs, the albumin predominates over globulin.
  • In horses, pigs, cow and cats albumin globulin ratio is equal. In new born animals (except rodents and primates plasma gamma globulin is absent or found in minute


Separation of plasma proteins


  • Salting out method: Using different concentrations of ammonium sulphate
  • Electrophoresis: Paper, starch gel, polyacrylamide gel electrophoresis are used for the separation of plasma protein



  • Transports thyroxine and Vitamin




  • Two fifth is intravascular and the rest occur extravascularly. It provides colloidal osmotic pressure because of its high concentration and low molecular weight and non-diffusible property through blood vessels, thus prevents excessive passage of fluid from the blood into the interstitial tissue and serves to control the fluid balance between blood and tissues.
  • It contributes to the amino acid pool with tissue protein and helps in transport of some anions and



  • Includes fractions α1 and α2, β1 and β2 and γ globulins which include IgA, IgD,IgE, IgG and
    • α – globulins act as carrier proteins of bilirubin, lipids, steroids and
    • α1 globulins are protease inhibitors and functions to inhibit WBC elastase and other WBC proteases and activated factor XI. The α1 lipoproteins transport lipids,fat soluble vitamins and
    • α2 globulins are the macroglobulins and inhibit plasmin, thrombin and
    • β – globulins are:
      • Ceruloplasmin: Transports
      • Ferroxidase: Transferrin transports
      • Haptaglobulin: Transports Hb to liver after haemolysis.
      • Apolipoproteins: Transports triglycerides, phospholipids and
      • Hemopexin: Aids the transport of heme from lysed
      • Transcortin: Transports
      • Transcobalamins I & II: Transports
    • γ – globulins
      • They provide viscosity to the blood, thus maintain normal blood pressure. Synthesised by -lymphocytes and plasma cells, functions to provide immunity and also helps transport of vitamin
      • The γ globulins are the immunoglobulins (Ig) and are classified into the following types:
      • IgG is responsible for most of the humoral immunity of the organism. It can cross placenta.
      • IgM is the second major immunoglobulin of the serum and it is typically the first   immunoglobulin   increase   in   concentration   in   serum during primary immune response. These are naturally occurring antibodies against erythrocytes in certain incompatible blood
      • IgA is a glycoprotein found in external secretion such as saliva, tears, colostrum etc. It forms the primary immunoglobulin in the colostrum and is responsible for natural passive immunity in the neo-natal calf, foal, lamb, kid and piglets. Plays an important role in local defence by protecting various body surfaces g., the intestinal, respiratory and uro-genital tracts, mammary gland and the eyes from bacterial and viral invasions. IgA does not cross the placenta. It is most abundantly found in normal animals.
      • IgD is involved in B-cell differentiation to form ‘clones’.
      • IgE is involved in hypersensitivity and allergic responses. It causes the release of histamine from basophils and mast cells.




  • Fraction from the liver, functions as a precursor to form a mesh work of fibrin threads and play a key role in blood
  • It influences the suspension stability of the erythrocytes. Increased concentration of fibrinogen and globulins alter the colloidal state of the blood, hastens agglutination of RBCs and
  1. Function as source of amino acids for the synthesis of tissue proteins. The amino acids of plasma protein and tissue proteins are in a state of dynamic
  2. Provide colloidal osmotic pressure and helps to regulate fluid balance. Around 80% of the colloidal osmotic pressure is contributed by
  3. They act as blood buffer and regulate acid-base balance, thus maintains normal pH of 4.
  4. Fibrinogen and various clotting factors are essential for coagulation of
  5. Influence the suspension stability of RBCs in the
  6. Contributes to the viscosity of plasma (by gamma globulins), thereby providing for peripheral resistance, which is essential for efficient cardiac
  7. As carrier proteins they are invloved in transport of copper, iron, heme, bilirubin, thyroxine, cortisol, sex hormones, vitamin A, vitamin D, fatty acids, triglycerides, phospholipids and
  8. Immunoglobulins provide specific antibody against specific


Species Total protein Albumin Globulin Fibrinogen
Horse 6.0 – 8.0 2.8 – 3.8 2.8 – 3.8 0.2-0.4
Cow 7.0 – 8.5 3.0 – 3.8 3.6 – 4.4 0.2-0.5
Sheep 6.0 – 8.0 3.5 – 4.5 2.5 – 3.5 0.2-0.4
Goat 6.5 – 7.5 3.7 – 4.5 2.4 – 3.2 0.2-0.5
Pig 6.5 – 8.5 3.5 – 4.0 3.5 – 4. 0 0.2-0.4
Dog 6.0 – 7.8 3.4 – 4.4 2.7 – 3.2 0.1-0.4
Cat 6.0 – 7.4 3.0 – 3.8 2.5 – 3.5 0.1 – 0.4
Fowl 4.0 – 5.2 1.2 – 3.8 2.3 – 3.3


  • Lipids are heterogenous molecules soluble in organic solvents but not in water. They are esters of fatty acids, formed by the reaction of fatty acids with
  • Blood lipids (or blood fats) are lipids in the blood and they are present either free or bound to other molecules. Blood lipids are mainly fatty acids, triglycerides, lipoproteins and
  • Since lipids are insoluble in water they are mostly transported in a protein covering, and the density of the lipids and type of protein determines the fate of the lipid and its influence on



  • The concentration of blood lipids depends on dietary intake, absorption from the intestine and excretion and uptake and secretion from cells.
  • Fatty acids are present in different forms {as in chylomicrons, Very low density lipoproteins (VLDL), Low density lipoproteins (LDL)} in In addition, the fatty acids released from adipocytes exist in the blood as free fatty acids.
  • Short- and medium chain fatty acids are absorbed directly into the blood via intestine capillaries and travel through the portal vein. Long-chain fatty acids are too large to be directly released into the intestine capillaries. Instead, they are coated with cholesterol and protein (protein coat of lipoproteins) into a compound called as chylomicrons. The chylomicrons enter into lymphatic capillary and then into the bloodstream (having bypassed the liver).
  • The concentration of blood fatty acids increase temporarily after a meal which increases the uptake of fatty acids in different cells of the body like liver cells, adipocytes and muscle cells. This uptake is stimulated by insulin from the
  • Some of the fatty acids taken up by the liver is converted into VLDL and again secreted into the blood.
  • When the concentration of fatty acids in the blood decreases, this triggers adipocytes to release stored fatty acids into the blood as free fatty acids, in order to supply the energy for the muscle cells and other cells.
  • Lipoproteins are complex aggregates of lipids and proteins that increases the solubility of lipids and enable their transport throughout the
  • Lipoproteins are synthesised mainly in the liver and
  • The most abundant lipid constituents of lipoproteins are triacylglycerols, free cholesterol, cholesterol esters and phospholipids (phosphatidylcholine and sphingomyelin); fat- soluble vitamins and anti-oxidants are also transported in this
  • The lipoproteins contain different protein components called apoproteins (or apolipoproteins). Apoproteins are required to solubilise the non-polar lipids in the circulation. These proteins determine the overall structures and metabolism, and their uptake in liver and peripheral
  • Lipoproteins are classified as chylomicrons (CM), very-low-density lipoproteins (VLDL), low-density lipoproteins (LDL) and high-density lipoproteins (HDL), based on the relative densities on ultracentrifugation.
  • Based on the relative mobilities on electrophoresis, lipoproteins can also be classified into α, pre-β and β lipoproteins that correspond to HDL, VLDL and LDL,


Density (g/ml) 0.94 0.94-1.006 1.006-1.063 1.063-1.210
Total lipids (wt%) 99 91 80 44
Triacylglycerol 85 55 10 6




Cholesterol esters 3 18 50 40
Cholesterol 2 7 11 7
Phospholipids 8 20 29 46


  • Lipoproteins are spherical in shape with the core containing non-polar lipids, triacylglycerols and cholesterol esters, and a surface layer consisting of phospholipids and non-esterified cholesterol, which also serve to present a hydrophobic face to the aqueous phase.
  • The principal role of the chylomicrons and VLDL is to transport triacylglycerols as a source of fatty acids from the intestines or liver to the peripheral
  • Chylomicrons: They are largest of the lipoproteins; they are formed in the intestinal mucosa and transport triacylglycerols from the intestinal mucosa to the liver or to other tissues; they carry mostly fats in the form of triglycerides and cholesterol. In the liver, chylomicron particles release triglycerides and some
  • VLDL: They are synthesised in liver. The liver converts the excess fatty acids (dietary or synthesised) into very low density lipoproteins (VLDL) and secretes them into plasma; in the plasma they are converted to intermediate density lipoproteins(IDL), and then to low- density lipoprotein (LDL) particles. VLDL transports triacylglycerols from liver to peripheral
  • LDL: It is the main transporter of cholesterol to the peripheral tissues. When they are present in excess they are strongly associated with the formation of atheromatous (plaque formation within arterial wall) disease within the For this reason, LDL is referred to as “bad cholesterol”.
  • HDL: They are synthesised in liver. The HDL removes excess cholesterol from peripheral tissues and delivers them to the liver for excretion in bile in the form of bile acids, a process that has been termed ‘reverse cholesterol transport’, helps to lower blood cholesterol level and hence HDL is commonly called “good cholesterol”.
  • After being transported to the liver by HDL, cholesterol is delivered to the intestines via bile production. However, 92-97% is reabsorbed in the intestines and recycled via enterohepatic circulation
  • It is lipid, waxy steroid found in the cell membranes and transported in the blood plasma of all animals.
  • It is an essential component of mammalian cell membranes where it is required to establish proper membrane permeability and
  • In addition, cholesterol is an important precursor molecule for the biosynthesis of bile acids, and several fat soluble vitamins, Vitamin D3 and the steroid hormones, includingthe adrenal gland hormones such as cortisol and aldosterone as well as the sex hormones like progesterone, estrogens, and testosterone and their
  • Within the cell membrane, cholesterol also functions in intracellular transport, cell signalling and nerve
  • Since cholesterol is essential for life, it is primarily synthesized de novo, within the body, with smaller contributions from the diet.
  • Excessive levels of cholesterol in blood circulation however are strongly associated with progression of


  • The fate of cholesterol in the blood is highly determined by its constitution of lipoproteins

– some types (LDL) favour transport towards body tissues and others (HDL) towards the liver for excretion into the intestines.

  • The average amount of blood cholesterol varies with age, typically rising gradually as age advances.
  • Hyperlipidemia refers to the elevated or abnormal levels of cholesterol and triacylglycerols in the blood. One of the most clinically relevant lipid substances is cholesterol, especially on atherosclerosis and cardiovascular
  • Lipemia is a term used to refer marked hyperlipidemic condition resulting in plasma presenting a milky white
  • Postprandial hyperlipidemia is most common in animals consuming fatty diet; hence to evaluate lipid status, blood samples have to be taken from fasting
  • Hyperlipidemia is noticed in dogs and man with hypothyroidism – main lipid increased is cholesterol. Pancreatitis, uncontrolled diabetes, cholestasis, hyperadrenocorticism are some other conditions causing
  • Hypercholesterolemia is the presence of high levels of cholesterol in the blood. It is not a disease but a metabolic derangement that can be secondary to many diseases and can contribute to many forms of disease, most notably cardiovascular




  • Animal fats are complex mixtures of triglycerides with phospholipids and cholesterol; hence, all foods containing animal fat contain cholesterol to varying
  • Cholesterol is not present in plant based food sources. However, plant products such as flax seeds and peanuts contain cholesterol-like compounds called phytosterols, which are suggested to help lower serum cholesterol levels.
  • About 20–25% of total daily cholesterol production occurs in the liver; other sites of high synthesis rates include the intestines, adrenal glands and reproductive
  • Synthesis within the body starts with one molecule of acetyl CoA and one molecule of acetoacetyl-CoA. HMG-CoA reductase is an important enzyme in the cholesterol synthesis. Total cholesterol is the sum of HDL cholesterol, LDL cholesterol and 20% of triglycerides.


Blood cholesterol levels in human beings


Type Level Remarks
Total cholesterol < 200 mg/dl Desirable level. Low risk for coronary disease
240 & above Hypercholesterolemia, high risk for coronary heart disease
HDL cholesterol <40 mg/dl Low HDL levels is the risk factor for cardiac disease
60 & above High HDL, protective to heart
LDL cholesterol < 100 mg/dl Desirable level
> 160 mg/dl High, risk of heart disease
Triglycerides < 150 mg/dl Normal
>200 mg/dl High




Total blood cholesterol levels (mg/100 ml) in animals


Species Blood cholesterol levels (mg/100 ml)
Horse 75-150
Cow 60-190
Sheep 52-90
Goat 80-130
Pig 80-134
Dog 135-270






Veterinary Physiology Question Bank


1. Anterior pituitary is embryologically developed from
a. Neural tube b. Neural crest c. Pharyngeal epithelium d. None

2. The most effective stimulus for cerebral circulation is
a. Oxygen deficiency b. Baro-receptor reflex c. Decreased glucose d.Excess CO2

3. Most of the blood clotting factors are produced in
a. Liver b. Lung c. Kidney d. Spleen

4. HCl and pepsin secretion in ruminants is by
a. Rumen b. Reticulum c. Omasum d. Abomasum

5. Increase in one hormone level in circulation may decrease the affinity of receptor for other
hormone by
a. Negative co-operativity b. Positive co-operativity
c. Permission action d. both b& c

6. Animal in which the internal temperature varies with external temperature are called as
a. Temperature regulators b. Temperature conformers
c. Heterotherms d. Endotherms

7. Bulbo-urethral gland is absent in
a. Dog b. Boar c. Bull d. Stallion

8. Split heat is usually observed in
a. Buffalo b. Bitch c. Mare d. Cow

9. Thermoregulation centre is located in
a. Hypothalamus b. Thalamus c. Motor cortex d. Hippocampus

10. Among the following domestic animals, sweating ability is highest in
a. Cattle b. Horse c. Sheep d. Goat

11. Major route of heat loss in cattle during high environmental temperature is by
a. Conduction b. Convection c. Radiation d. Evaporation

12. Site of formation of CSF is
a. Choroid plexus b. Astrocytes c. Meninges d. Sinuses

13. Type of sensory receptors involved in initiation of micturition reflex is
a. Chemoreceptors b. Nociceptors c. Osmoreceptors d. Stretch receptors

14. Pancreatic bicarbonate secretion is enhanced by
a. Secretin b. Motilin c. Cholecystokinin d. Gastrin20

15. Sympathetic post-ganglionic neurotransmitter is
a. Nor-epinephrine b. Acetylcholine c. Serotonin d. 5-HT

16. Sertoli cells of testes secrete
a. Inhibin b. Estrogen c. Androgen binding protein d. All

17. Which one of the following circulatory division has the lowest pressure?
a. Capillaries b. Arteries c. Veins d. Arterioles

18. Which segment of the renal tubule is impermeable to water?
a. Proximal convoluted tubule b. Thick segment of ascending loop of Henle
c. Collecting duct d. Thin segment of descending loop of Henle

19. Cardiac output can be represented by the formula
a. Stroke Volume/Pulse rate b. Stroke Volume – Pulse rate
c. Stroke Volume X Pulse rate d. Pulse rate/Stroke Volume

20. During atrial systole, the ventricles are in a state of
a. Systole b. Diastole c. Iso-volumic contraction d. None

21. Which one of the following neurotransmitter is inhibitory in nature?
a. GABA b. Acetyl choline c. Glutamic acid d. Adrenaline

22. Avascular structure of eye is
a. Cornea b. Sclera c. Iris d. Lens

23. Among glial cells, one of the following is highly phagocytic
a. Astrocyte b. Microglia c. Schwaan’s cell d. Oligodendrocytes

24. Gaseous exchange at tissue level is referred as
a. Breathing b. Ventillation
c. Internal respiration d. External respiration

25. “The breeds which inhabit warm and humid regions have more melanin pigmentation
than those of the same species in cooler and drier region” is
a. Golger’s rule b. Bergman’s rule c. Allen’s rule d. Wilson’s rule

26. Substance used to measure total body water by dye dilution technique is
a. Antipyrine b. Insulin c. Thiosulfate d. Inulin

27. A biological rhythm of 24 hrs duration is known as
a. Ultradian rhythm b. Circadian rhythm c. Infra-red rhythm d. Annual rhythm

28. Part of the brain important for smooth, accurate and coordinated movement is
a. Hypothalamus b. Cerebrum c. Cerebellum d. Thalamus

29. CO2 is mainly transported in blood as
a. Carbaminohemoglobin b. Carboxyhemoglobin
c. Oxyhemoglobin d. Bicarbonate ions 21

30. The substance that constitute maximally to the osmolarity inside the cells is
a. Protein b. Phosphate c. Urea d. Potassium

31. The term ‘Milieu interior’ was introduced by
a. Cunningham b. Boyle c. Claud Bernard d. Arthur C Guyton

32. S.A.Node is the pacemaker of heart because of
a. Location in the right atrium b. Neural control
c. Natural leakiness to Na+
d. Natural leakiness to K+

33. Increased vagal tone causes
a. Hypertension b. Tachycardia c. Bradycardia
d. Increase in cardiac output

34. The hormones secreted by group of cells which have actions on nearby cells are known as
a. Endocrine b. Autocrine c. Paracrine d. Neurocrine

35. Biological action of hCG is similar to that of
a. FSH b. LH c. Prolactin d. Inhibin

36. Zona glomerulosa mainly secretes
a. Glucocorticoids b. Mineralocorticoids c. Sex steroids d. None

37. Which of the following is not a protein hormone
a. FSH b. Growth Hormone c. Thyroxine d. Relaxin

38. The receptors for thyroid hormones are situated on
a. Cell membrane b. Cytoplasm c. Nucleus d. Golgi apparatus

39. Melatonin hormone is secreted by
a. Pineal gland b. Post. Pituitary c. Adrenal cortex d. Hypothalamus

40. Diabetes insipidus is because of deficiency of
a. Insulin b. Inulin c. Insulin receptors d. ADH

41. Hormone essential for let down of milk is
a. Oxytocin b. Prolactin c. Placental lactogen d. Thyroxine

42. The most potent mineralocorticoid is
a.Cortisol b. Aldosterone c. Dexamethasone d. Testosterone

43. Blood calcium level is increased by
a.Calcitonin b. Parathyroid hormone c. Thymulin d. Aldosterone

44. One of the following hormone is an amino acid derivative
a. Epinephrine b. Norepinephrine c. Thyroxine d. All of them

45. Name the hormone, predominantly produced in response to fight, fright and flight
a. Thyroxine b. Aldosterone c. Epinephrine d. ADH22

46. The hormone essentially required for the implantation of fertilized ovum and maintenance
of pregnancy
a. Progesterone b. Estrogen c. Cortisol d. Prolactin

47. The precursor for the synthesis of steroid hormones is
a. Acetic acid b. Cholesterol c. Dopamine d. Tyrosine

48. Insulin is secreted by__________ cells of islets of langerhans
a. Alpha-cells b. Beta-cells c. Gamma-cells d. Delta-cells

49. Which of the following acts as second messenger?
a. cAMP b. Inositol triphosphate c. Calmodulin d. All of them

50. The hormone that stimulates gall bladder contraction and release of pancreatic enzymes
a. Gastrin b. Secretin c. Cholecystokinin d. Pancreatic polypeptide

51. The receptors for steroid hormones are found on
a. Cell membrane b. Cytoplasm c. Nucleus d. Mitochondria

52. The concentration of hormone in the blood can be measured by
a. ELISA b. RIA c. EIA d. All of them

53. Among the following, smallest erythrocytes are found in
a. Dog b. Goat c. Cattle d. Poultry

54. Natural anticoagulant heparin is produced by
a. Mast cells b. Platelets c. Macrophages d. Band cells

55. Chief site of plasma protein synthesis
a. Liver b. Brain c. lung d. Intestine

56. Normal resting membrane potential of SA node
a. -55 mV b. -80mV c. -90mV d. -75mV

57. Pernicious anemia is due to
a. Deficiency of Vit-B12 b . Deficiency of cobalt
c. Inability to produce intrinsic factor d. Deficiency of folic acid

58. S3 and S4 cardiac sounds are very common in
a. Horse b. Cattle c. Goat d. Dog

59. Erythrocytes in camel are
a. Elliptical & Non-nucleated b. Biconcave & Nucleated
c .Discoid & Non-nucleated d. Elliptical & Nucleated

60. The conduction of cardiac impulses is highest in
a. SA Node b. AV Node c. AV bundle d. Purkinje Fibers

61. Ability of the cardiac muscle to generate spontaneous wave of depolarization is called
a. Ionotropism b. Chronotropism 23
c. Staircase Phenomenon d. Functional syncytium

62. Which of the following condition shifts the Oxygen-Hemoglobin curve to the left
a. Acidic pH b. 2, 3-Diphosphoglycerate c. High temperature d. Fetal Hb

63. Fick’s principle is used to measure
a. Arterial pressure b. Cardiac output c. Stroke volume d.Venous pressure

64. Mean arterial pressure is highest in
a. Poultry b. Cattle c. Horse d. Dog

65. Yellow coloration of the blood plasma in horse is attributed to
a. Bilirubin b. Hemoglobin c. Biliverdin d. Cholic acid

67. Largest descending tract of the spinal cord is
a. Rubrospinal tract b. corticospinal tract
c. Reticulospinal tract d. Tactospinal tract

68. An example for monosynaptic reflex
a. Withdrawal reflex b. Myotatic reflex c. Blink reflex d. Scratch reflex

69. Silent area of the brain is
a. Cerebellum b. Cerebrum c. Pons d. Medulla oblongata

70. Dyslexia is caused by the lesion in the
a. Visual sensory area b. auditory sensory area c.Wernick’s area d. Broca’s area

71. Anterograde amnesia is caused by the lesion in the
a. Amygdala b. Hypothalamus c. Thalamus d. Hippocampus

72. An example for amylolytic bacteria is
a. Bacteroides ruminicola b. Butyrivibrio fibrisolvens
c. Ruminicoccus bromii d. Traponema bryantii

73. Number of bacteria per gram of rumen content is higher in ruminants that are fed with
a. Green fodder b. Dry fodder c. Concentrates d. Hay

74. The chemical that is used for defaunation is
a. Calcium chloride b. Calcium carbonate c.Calcium peroxide d. Sodium chloride

75. Key intermediate of rumen carbohydrate fermentation is
a. Butyrate b. Acetate c. Propionate d. Pyruvate

76. Synthesis of milk fat in ruminants requiresa. Butyric acid b. Propionic acid c. Lactic acid d. Carbonic acid

77. Structure involved in gaseous exchange in birds
a. Alveoli b. Septum c. Bronchi d. Parabronchi

78. Blood volume accounts for ___________ % of body weight
a. 80% b. 0.8% c. 8% d. 0.6% 24

79. Expansion of the lungs with each unit increase in transpulmonary pressure is called
a. Distensibility b. Compliance c. Recoiling pressure d. Elasticity

80. RMP in resting cells is due to activity of
a. Na+-K+ ATPase pump b. Voltage gated Na+ channels
c. Voltage gated K+ channels d. Chloride channels

81. The different events that follow during the estrus cycle are
a. Increased FSH, ovulation, luteinization, LH surge.
b. Luteinization, Increased FSH, ovulation, LH surge.
c. Increased FSH, LH surge, ovulation, luteinization.
d. Increased FSH, ovulation, LH surge, luteinization.

82. Blood osmotic pressure is mainly due to
a. Water b. Blood cells c. Plasma proteins d. None

83. Which is the highly sensory stimulus for salivary secretion?
a. Taste b. Smell c. Vision d. Excitement

84. A substance which increases the salivary secretion is called:
a. Anhidrotic b. Sialogogus c. Diuretic d. Cholorectics

85. It is not the function of bile salts:
a. Emulsfication b. Lowering the surface tension
c. Hydrolysis of lipids d. Increasing the surface tension

86. Gibbs-Donnan effects leads to
a. Non-diffusible ion between two sides will be equal
b. diffusible ions between two sides will be equal
c . Equal passive diffusion
d. Osmotic gradient

87. The principal cation in the extracellular fluid is
a. Na+
b.K c. Ca2+ d.Mg2+

88. Increased GFR caused by
a. Increased cardiac output b. Afferent arteriolar vasoconstriction
c. Efferent arteriolar vasodilatation d.Increased chloride delivery to macula densa

89. Which of the following carbohydrate is present in seminal fluid and not produced
anywhere in the body
a.Glucose b.Fructose c. Ribose d.Lactose

90. An ECG would be useful for determining a patients
a. Heart murmur b. Stroke volume c. Cardiac ouput
d. Blockage of conduction of electrical signal between the atria and the ventricle25

91. According to the Frank-Starling mechanism of the heart
a. The left ventricle ejects a large volume of blood with each systole than the right
b. The intrinsic rate of heart’s pacemaker is 100 beats/min
c. Cardiac output increased with increased heart rate
d. Stroke volume increased with increased venous return

92. Retention of sodium in the body leads to a retention of
a. Potassium b. Water c. both a & b d. neither a or b

93. Which of the following statements is correct?
a. Thyroxine inhibits utilization of glucose
b . Insulin increases utilization of glucose
c. Glucagon promotes muscle glycogenolysis
d. Insulin inhibits lipogenesis from carbohydrates

94. All the following hormones use cAMP as a second messenger except
a. Estrogen b. FSH c. Luteinizing d. Glucagon
95. The type of placenta in bitches is
a. Epitheliochorial b. Endotheliochorial c. Syndesmochorial d. Haemochorial

96. The hormones secreted during non-shivering thermogenesis are
a. Epinephrine and thryoxine b. Cortisol and insulin
c. GH and oxytocin d. Insulin and glucagon

97. Cryptorchidism means
a. Descent of testis b. Hypogonadism
c. Hyperfunction of testis d. Undescended testis

98. Erythropoietin
a. Contains iron b. has no effect on WBC
c. Stimulates renin secretion d. Increases half life of RBC

99. Which of the following is not increased during exercise
a. Stroke volume b. Total peripheral resistance c. Systolic pressure d. Heart

100. Iron is absorbed in
a. Stomach b. Duodenum c. Jejunum d. Ileum

101. Smooth muscle need help of
a. Calmodulin for contraction b. Acetyl choline for contraction
c. K+ for contraction d. Monoamine oxidase for contraction

102. The cross bridges of the sarcomere in skeletal muscle are components of26
a. Actin b. Myosin c. Troponin d. Tropomyosin

103. The likely mechanism through which neostigmine acts in improving muscular weakness
a. It blocks action of acetylcholine
b. It interferes with action of mono-amine oxidase
c. It enhances the action of catecholamines
d. It blocks action of acetyl choline esterase

104. A skeletal muscle
a. Obeys all or none phenomenon
b. Becomes less excitable when its membrane becomes hyperpolarized
c. Has a resting membrane potential positive inside
d. Contains excessive Na+ in intracellular compartment

105. Cellular immunity is due to
a. B lymphocytes b. T lymphocytes c. Neutrophils d. Eosinophils

106. Action of plasmin is
a. to remove calcium b. Antithrombin action
c. To stimulate heparin d. To degenerate fibrin

107. Osmotic pressure of plasma is mainly maintained by
a. Albumin b. Alpha globulin c. Beta globulin d.Gamma globulin

108. Which is the most rare human blood group
a. A Rh+ b. AB Rh+ c. AB Rh- d. B Rh109. Hematocrit of

109. 45% means that in the sample of blood analysed
a. 45% Hb is in the plasma b. 45% of total blood volume is made up of plasma
c. 45% of Hb is in the RBC d. 45% of the total blood volume is made up of
RBC’s and WBC’s

110. Positive bathmotropic effect on heart is produced by
a. Stimulation of vagus nerve b. Stimulation of sympathetic nerves
c. Atropin d. Sectioning of vagus

111. Mary’s law denotes relationship between heart and
a. Contractility and conductivity b. Rate and contraction
c. Rate and BP d. Contraction and BP

112. Which of the following conducting systems has the slowest conducting velocity
a. SAN b. Atrial muscle c. Purkinje fibres d. AVN

113. In heart, within physiological limits the force of contraction is directly proportional to
a. Pacemaker activity b. A-V nodal delay27
c. Initial length of the cardiac muscle d. Respiratory rate

114. The diacrotic notch on aortic pressure curve is caused by
a. Closure of mitral valve b. Closure of tricuspid valve
c. Closure of atrial valve d. Closure of pulmonary valve

115. The PR interval of ECG corresponds to
a. Ventricular repolarization b. Ventricular repolarization
c. Atrial repolarization and conduction through AV node
d. Repolarization of AV node and bundle of His

116. Increased vagal tone causes
a. Hypertension b. Tachycardia
c. Bradycardia d. Increase in cardiac output

117. Which of the following is not increased during exercise
a. Stroke volume b. Total peripheral resistance c. Systolic BP d.Heart rate

118. Which of the following takes longest time to return to normal after 1L of blood is
removed from a normal individual
a. Number of RBC’s in peripheral blood b. Plasma volume
c. Renin secretion d. Blood pressure

119. When a pheochromocytoma suddenly discharges a large amount of epinephrine into the
circulation the patients heart rate would be expected to
a. Increase because epinephrine has a direct chronotropic effect on the heart
b. Increase because of increased parasympathetic discharge to the heart
c. Decrease because the increase in blood pressure stimulates the carotid and aortic
d. Decrease because of increased tonic parasympathetic discharge to heart

120. As one ascends to higher than 3000meters above sea level changes in alveolar PO2 and
PCO2 are as follows
a. Decrease in PO2, increase in PCO2 b. Decrease in PO2, decrease in PCO2
c. Increase in both PO2 and PCO2 d. Increase in PO2, decrease in PCO2

121. Surfactant is secreted by
a. Type 1 pneumatocytes b. Type 2 pneumatocytes
c. Goblet cells d.Pulmonary vessels

122. Which of the following effects is not observed during prolonged stay is space
a. Decrease in blood volume b. Decrease in muscle strength
c. Increase in red cell mass d. loss of bone mass

123.Which of the following discharge spontaneously during quiet breathing28
a. Stretch receptors in lung b. Motor neurons in respiratory muscles
c. Dorsal respiratory group of neurons d. Ventral respiratory group of neurons

124. Pneumatic center functions primarily to
a. Limit inspiration b. Prolong expiration
c. Decrease rate d. Discharge inspiratory action potential

125. Which of the following is the effect of negative G on the eye
a. Temporary blinding with redout b. Blackout of vision within few seconds
c. No effect d. Redout and blackout

126. Airway resistance
a. Increases in asthama b. Decreases in emphysema
c. Increases in paraplegic patients d. Does not affect work of breathing

127. Decrease on PCO2, decrease in H+ and increased PO2 causes
a. Hyperventilation b. Hypoventilation c. Hypercapnoea d. Hypoxia

128. Herring-Breur inflation reflex in human being
a. Decreases the rate of respiration
b. Is not activated until the tidal volume increases above 1.5 lit
c. Is an important factor in normal control of ventilation
d. Is activated only when tidal volume is les than 1 lit.

129. Total vital capacity is decreased but timed vital capacity is normal in
a. Bronchial asthama b. Scoliosis c. Chronic bronchitis d. All

130. The intrapleural pressure at the end of deep inspiration is
a. – 4mm Hg b. + 4 mm Hg c. – 6mm hg d. + 6 mm Hg

131. Premotor cortex refers to
a. Some areas anterior to primary motor cortex causing complex co-ordinate
movements like speech; eye moment
b. An area of motor cortex responsible for voluntary movements
c. An area in temporal cortex
d. An area of cerebellum

132. Functions of limbic system are all EXCEPT
a. Olfaction b. Gustation c. Feeding behaviour d.Sexual behaviour

133. REM is
a. Characterised by delta waves on ECG
b. A sound and dreamless sleep
c. Characterised by total lack of muscular activity
d. Referred to as paradoxical sleep29

134. Sleep deprivation
a. Can cause psychotic episodes b. Is associated wit sluggishness of thoughts
c. Makes a person more alert d. Has no effect on the individual

135. The sympathetic system
a. Has short post ganglionic fibres b. Consists of vagus nerve
c. Produces nicotine at its nerve endings
d. Has a thoraco-lumbar outflow from the spinal cord

136. Visceral pain
a. Shows relatively rapid adaptation
b. Is mediated by beta fibres in dorsal root of spinal nerves
c. Can sometimes be relieved by applying irritant to skin
d. Can be produced by prolonged stimulation of touch receptors

137. The naked nerve endings are responsible for the sensation of
a. Pain b. Touch c. Hearing d. Vision

138. When a normally innervated skeletal muscle is stretched the initial response is
contraction, with increase in the stretch sudden relaxation occurs because of
a. Decrease in gamma efferent discharge
b. Inhibition of the discharge from annulospiral endings of afferent nerve fibres
c. Decreased activity of afferent nerve fibres from golgi tendon organs
d. Increased activity of afferent nerve fibres from golgi tendon organs
139. After anterolateral cordotomy relief of pain is due to interruption of
a. Left dorsal column b.Left ventral spinothalamic tract
c. Right lateral spinothalamic tract d.Left lateral spinothalamic tract

140. Parasympathetic system
a. Has short preganglionic fibres b. Secretes dopamine
c. Controls most of the movements and secretions of gut
d. Brings increase in heart rate during exercise

141. Hypopituitarism is characterized by
a. Infertility b. Intolerance to heat c. Weight gain
d. Excessive growth of the soft tissue

142. Excessive growth hormone secretion in adults causes
a. acromegaly b. gigantism
c. increased entry of glucose in muscles d. hypothyroidism

143) Angiotensin increases blood pressure by acting on the following EXCEPT
a. Aldosteron secretion b. Vascular smooth muscle30
c. Parasympathetic nervous system d. Sympathetic nervous system

144. Erythropoietin
a. Contains iron b. Has no effect on WBC count
c. Stimulates renin secretion d. Increases half life of RBC

145. Somatostatin
a. Inhibits insulin and glucagoon release b. Stimulates insulin and glucagon release
c. Stimulator of glucagon release d. Acts as obesity hormone

146. Testosterone is secreted by
a. Sertoli cells of testis b. Cells of adrenal medulla
c. Cells of hypothalamus d. Leydig cells of testis

147. Cryptorchidism means
a. Descent of testis b. Hypogonadism
c. Hyperfunction of the testis d. Undescended testis

148. Androgen binding protein is produced by
a. Adrenals b. Hypothalamus c. Sertoli cells d. Leydig cells

149. All of the following are produced by the corpus leuteum except
a. Estrogens b. Progesteron c. Relaxin d. F.S.H.

150. The testis is kept at a temperature of 2-3 degrees C below core temperature due to
a. Contraction of cremasteric muscle b. Contraction of dartos muscle
c. Contraction of internal oblique muscle
d. Relaxation of cremasteric muscle and due to position of testis outside pelvic cavity

151. The somatic cells containing the full complement of 46 chromosomes in their nuclei,
containing all the genes necessary for carrying out the cell activities are called
a. Autosomes b. Haploid cells c. Allosomes d. Diploid cells

152. In some cases DM is due to
a. Excessive receptors b. Antibodies against receptors
c. Deficiency of receptors for extra cellular proteins
d. Deficiency of nucleotide regulatory G proteins

153. Many substances are removed from the cell to outside by
a. Pinocytosis b. Chemotaxis c. Phagocytosis d. Exocytosis

154. Excessive formation of a substance/ secretion in the body is controlled in order to
maintain Homeostasis is
a. +Ve feedback mechanism b. -Ve feedback mechanism
c. Osmosis d. Haemodynamics

155. An action potential in a nerve31
a. Is terminated by influx of Na+ excessive receptors b. Is terminated by efflux of K+
c. Is initiated by efflux of Na+ d. Is initiated by influx of K+

156. ” Milieu interior ” is a term introduced by
a. Laplace b. Boyle c. Claud Bernard d. Lansteiner

157. An example of co-transport is
a. Na+-K+ pump b. Ca++ pump c. Na+- H+ pump d. Na+ glucose transport

158. The function of tropomyosin in skeletal muscle is-
a. Sliding on actin to produce shortening
b. Releasing Ca++ after initiation of contraction
c. Binding to myosin during contraction
d. Covering up the actin binding sites of myosin at rest

159. The normal A/G ratio in blood is
a. 1:2 b. 2:1 c. 1:3 d. 3:1

160. Which of the following statements concerning the monocyte is incorrect
a. More common in blood than eosinophils and basophils
b. Produced in the adult by the bone marrow and lymph nodes
c. Unlike neutrophil does not accumulate outside circulation in area of inflammation
d. Not classified as a granulocyte

161.The normal non fasting blood ketone level is
a. 0.1 – 0.5 mg% b. 0.5- 2 mg% c. 2- 10 mg % d. 100 – 500 mg%

162. The ‘T’ wave in ECG is above the isoelectric line because of
a. Depolarisation of ventricles
b. Depolarisation of bundle of His
c. Change in direction of repolarisation from wave of depolarization of the ventricles
d. Repolarisation of purkinje fibres

163. The ‘s’ wave in ECG is below isoelectric line because of
a. Repolarization of ventricles
b. Change in direction of impulse when base of the ventricles are getting depolarised
c. Depolarisation of apex of heart
d. Repolarisation of apex of heart

164. Which of the following is least likely to cause hypertension?
a. Chronically increased secretion of adrenal medulla
b. Treatment with OCP
c. Chronically increased secretion of thyroid gland
d. Chronically increased secretion by zona glomerulosa of adrenal cortex32

165. Lymph flow from the foot is
a. Increased when an individual rises from the supine to standing position
b. Increased by massaging the foot
c. Increased when capillary permeability is decreased
d. Decreased by exercise

166.The pressure in the radial artery is determined by
a. The degree of constriction of brachial vein
b. The rate of discharge in sympathetic nerve fibres to the arm
c. Pressure in the hepatic portal vein
d. Pressure in the brachial vein

167. Saliva is responsible for all EXCEPT
a. Helps in deglutition b. Prevents dental carie
c. Is essential for complete digestion of starch d. Prevents decalcification of the teeth

168. Steatorrhoea may be caused by all factors except
a. Pancreatectomy b. Gastrin secreting hormone
c. Resection of distal ileum d. Hemolytic jaundice

169. Normal swallowing is dependant on the integrity of the
a. 9th and 10th cranial nerves b. Pyramidal tract
c. Trigeminal nerve d. Appetite center of hypothalamus

170. Secretion of intrinsic factor occurs in
a. Parietal cells of stomach b. Chief cells of stomach
c. Upper abdomen d. Alpha cells of pancreas

171. In which of the following is absorption of water greatest
a. Colon b. Jejunum c. Duodenum d. Stomach

172. Secretin is released by
a. Acid in duodenum b. Acid in stomach
c. Cells in the liver d. Distention of colon

173. Which of the following would not be produced by total pancreatectomy?
a. Hyperglycaemia b. Metabolic acidosis
c. Weight gain d. Decreased absorption of amino acids

174. Vit D is essential for normal
a. Fat absorption b. Ca absorption c. ADH secretion d.Protein absorption

175. Gastrin secretion is increased by
a. Acid in the lumen of stomach b. Distension of stomach
c. Increased circulating levels of secretin d. Vagotomy33

176. In a health adult sitting with eyes closed the EEG rhythm observed with electrodes on
occipital lobes
a. Alpha b. Theta c. Delta d. Beta

177. The basal ganglia are primarily concerned with
a. Sensory integration b. Short term memory
c. Control of movement d. Neuroendocrine control

178. Interruption of motor pathways in the internal capsule on one side causes
a. Spastic paralysis on the same side b. Spastic paralysis on the opposite side
c. Flaccid paralysis on the same side d. Flaccid paralysis on the opposite side

179. The extrapyramidal system is not concerned with
a. Stretch reflex b. Righting reflex c. Spasticity d. Sensation of viscera

180. Non fluent aphasia is produced by lesion of
a. Brocas area b. Angular gyrus c. Parietal lobe d. Frontal lobe

181. Thirst is stimulated by
a. increase in plasma osmolality and volume
b. increase in plasma osmolality and decrease in volume
c. decrease in osmolality and increase in volume
d. decrease in plasma osmolality and volume

182. Lesions of which of the following hypothalamic nuclei cause loss of circadian rhythm
a. Ventromedial b. Dorsomedial c. Suprachiasmatic d. Supraoptic

183. Normal blood flow to the brain is
a. Greatly modified by vasomotor control b. About 150ml/min
c. About 750ml/min d. Greatly increased during exercise

184. Retrograde amnesia
a. Is abolished by prefrontal lobectomy
b. Responds to drugs that block dopamine receptors
c. Is commonly precipitated by a blow on the head
d. Is commonly precipitated by ageing

185. A meal rich in proteins but low in carbohydrates does not cause hypoglycaemia because
a. Glucagon secretion is stimulated by meals
b. The meal causes compensatory increase in T4 secretion
c. Cortisol in circulation prevents glucose from entering the muscles
d. The amino acids in the meal are converted to glucose

186. Which of the following is incorrectly paired
a. Beta cells-insulin b. F cells- gastrin 34
c. Delta cells- somatostatin d. Alpha cells- glucagon

187. After intravenous administration of a large dose of insulin, the return of a low blood
sugar level to Normal is delyed by
a. Thyrotoxicosis b. Glucagon deficiency
c. Diabetes d. Parathormone deficiency

188. Insulin increases entry of glucose into
a. Renal tubule b. The mucosa of the small intestine
c. Neurons of motor cortex d. Skeletal muscle cells

189. Glucagon is not normally found in the
a. Brain b. Pancreas c. Git d. Adrenal glands

190. Which of the following is NOT produced by physiological amounts of glucocorticoids
a. Maintenance of normal vascular reactivity b. Inhibition of inflammatory response
c. Increased excretion of a water load d. Inhibition of ACTH secretion

191. Cortisol increases blood glucose level by
a. Increasing lipolysis b. Increasing protein synthesis in muscles
c. Increasing gluconeogenesis d.Increasing growth hormone secretion

192. Epinephrine and norepinephrine
a. Are amino acids b. are both secreted by neurons in autonomic nervous system
c. Are polypeptides d. Both activate alpha and beta adrenergic receptors

193. A decrease in extracellular volume is expected to cause increased secretion of all except
a. Vasopressin b. Renin c. Thyroxin d. ACTH

194. Thyrocalcitonin
a. Is secreted by thyroid b. Is secreted by hypothalamus
c. Is secreted by parathyroid d. Increases Ca++ absorption by stomach

195. Which of the following is not involved in regulation of plasma Ca++ levels
a. kidneys b. skin c. lungs d. intestine

196. Ca++ plays an important role in following biological processes except
a. Oxygen utilization b. Contraction of cardiac muscle
c. Contraction of skeletal muscle d. Blood coagulation

197. Epiphyseal closure is regulated by
a. Calcitonin b. Somatomedins c. 1,25 dihydroxy cholecalciferol d. Thyroxine

198. Which of the following pituitary hormones is a polypeptide
a. MSH b. ACTh c. Beta – endorphin d. Growth hormone

199. Growth hormone acts directly on
a. Stimulation of protein synthesis b. Stimulation of cartilage formation35
c. Elevation of BSL d. Stimulation of bone formation

200. Inhibin is secreted by
a. Graffian follicle b. Corpus leuteum c. Endometrium d. Placenta


1 C 11 D 21 A 31 C 41 A 51 B 61 B 71 D 81 C 91 D
2 D 12 A 22 D 32 C 42 B 52 D 62 D 72 A 82 C 92 B
3 A 13 D 23 B 33 C 43 B 53 B 63 B 73 A 83 C 93 D
4 D 14 A 24 C 34 C 44 D 54 A 64 A 74 C 84 B 94 A
5 A 15 A 25 A 35 B 45 C 55 A 65 A 75 D 85 D 95 B
6 B 16 D 26 A 36 B 46 A 56 A 66 C 76 B 86 D 96 A
7 A 17 C 27 B 37 C 47 B 57 C 67 B 77 D 87 A 97 D
8 B 18 B 28 C 38 C 48 B 58 A 68 B 78 C 88 A 98 B
9 A 19 C 29 D 39 A 49 D 59 D 69 A 79 B 89 B 99 B
10 B 20 B 30 C 40 D 50 C 60 D 70 C 80 A 90 D 100 B

101,a 102,b 103,d 104,a 105,b 106,d 107,a 108,c 109,d 110,b
111,c 112,c 113,c 114,c 115,c 116,c 117,b 118,a 119,a 120,b
121,a 122,c 123,c 124,a 125,a 126,a 127,b 128,b 129,b 130,a
131,a 132,b 133,d 134,a 135,d 136,c 137,a 138,d 139,d 140,c
141,a 142,a 143,c 144,b 145,a 146,d 147,d 148,c 149,d 150,d
151,d 152,d 153,d 154,b 155,b 156,c 157,d 158,d 159,b 160,c
161,c 162,c 163,b 164,c 165,b 166,b 167,c 168,d 169,a 170.b
171,b 172,a 173,c 174,b 175,b 176,a 177,c 178,b 179,d 180,b
181,d 182,c 183,c 184,c 185,a 186,b 187,b 188,d 189,d 190,b
191,c 192,d 193,c 194,a 195,c 196,a 197,b 198,c 199,c 200,a

Veterinary Physiology

Veterinary Physiology

Introduction to Blood;Properties of blood as a body fluid, metabolism and fate of R.B.C;Hemoglobin-chemical structure, synthesis, physiological functions, derivatives of hemoglobin;Heart- morphological characteristic, systemic excitability conduction and transmission processes.

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The heart is in the thoracic cavity within the mediastinum between the left and right pleural cavities and protected by the ribs from about the third to the sixth intercostal spaces. The dorsal aspect is horizontally in line with the middle of the first rib and the ventral aspect is on the sternum. The long axis of the cardiac silhouette is oriented vertically in the horse, almost vertically in ruminants, and progressively more obliquely in the pig, dog, and cat. The dorsal part of the heart is known as the base and is formed by the atria and the major vessels entering (veins) and leaving (arteries) the heart. The major vessels tend to hold the heart in a relatively fixed position dorsally while ventrally it is free within the pericardial sac.

The heart is actually two separate pumps: a right heart that pumps blood through the lungs, and a left heart that pumps blood through the peripheral organs. In turn, each of these hearts is a pulsatile two-chamber pump composed of an atrium and a ventricle. Each atrium is a weak primer pump for the ventricle, helping to move blood into the ventricle. The ventricles then supply the main pumping force that propels the blood either (1) through the pulmonary circulation by the right ventricle or (2) through the peripheral circulation by the left ventricle.

The cardiovascular system has two circulations in series:

  • (i) the Pulmonary circulation composed of the right atrium (RA), right ventricle (RV) and lungs; and
  • (ii) the Systemic circulation composed of the left atrium (LA), left ventricle (LV), and the systemic organs.

Each circulation has three major divisions:

  • (i) the distribution system (ventricles, arteries, and arterioles),
  • (ii) the perfusion/exchange system (capillaries), and
  • (iii) the collecting system (venules, veins, and atria).

[ A Portal system is defined as two capillary beds connected in series between an artery and a vein.

  • In the renal circulation, there is a glomerular capillary bed between two arterioles and another normal capillary bed between an arteriole and a venule.
  • Another portal system is shown in the digestive venous circulation as it drains into the liver via the portal vein. Additionally, the liver has an arterial supply for delivery of oxygen and nutrients.
  • A third portal system occurs in the hypothalamus/pituitary area of the cranial blood flow. ]

Physiology of Cardiac Muscle:

The heart is composed of three major types of cardiac muscle: atrial muscle, ventricular muscle, and specialized excitatory and conductive muscle fibers. Cardiac muscle is striated in the same manner as in skeletal muscle. Further, cardiac muscle has typical myofibrils that contain actin and myosin filaments almost identical to those found in skeletal muscle; these filaments lie side by side and slide along one another during contraction in the same manner as occurs in skeletal muscle. But in other ways, cardiac muscle is quite different from skeletal muscle, as we shall see.

Myocardial cells: Functional syncytium(Present), Morphological syncytium(Absent).

Atrial functional syncytium is present from Ventricular functional syncytium by- Annulus fibrosi(Physical attachment of atrium & ventricles)

[Annulus fibrosi: A fibrous structure electrically insulates the atrium from the ventricles and physically forms the attachment rings called Annulus fibrosi.

An opening exits in the fibrous plate for the Atrio-ventricular bundle to conduct impulses from the atrial to ventricles]

Myocardial Cells

Spontaneous depolarization:- The normal pacemaker of the heart is SA node.(Right atrium)

Spontaneous phase-4 depolarization of these cells initiates an action potential that is conducted throughout the heart. Other slower pacemakers are located in the AV node & the His-Purkinje system.

Slower pacemaker may capture normal pacemaker rhythm if they fire more rapidly or normal pacemaker becomes slower.

Myocardial cells are capable of transmitting action potential that can pass from cells to cells through gap jn.

White muscle fibers are found in Eye ball,Gastronemius,Biceps brachii.In these fibres anaerobic energy production is seen.


Propagation of action potentials throughout the heart required depolarization of a cardiac cell from arresting state to an excited state.

Propagation of cardiac action potential requires the flow of electrical current(charge).

Charge carriers: Na+, K+ , Ca++

Anions are generally large charge proteins that cannot easily diffuse across cell membranes, except Cl-

Flow of charge depends on-

i.Diving force: a) Potential difference & b) Concentration difference

ii.Path [Channel]: Voltage gated, Time depended, State of Phosphorylation

  • Membrane potential b/w the inside & the outside the cells=Electrical diving force
  • Concentration difference b/w the inside & outside the cell=Chemical diving force

Generation of an Action Potential:-

i.Generation of Polarizes state



(i) Generation of a polarized state: Polarization of the cardiac cell results from a selective permeability to K+, which allows K+ to flow out of the cell down its concentration gradient.

K+ efflux: Intracellular Positive ion balance alters—à Generation of Negative intracellular potential–à Negative potential reduce K+ efflux diving force= K+ equilibrium Potential

Thus, the resting cardiac cell is polarized, in that the interior of the cell represents a negative pole, whereas the exterior represents a positive pole.

  • If positive charge is added to the inside of the cell, the cell becomes less polarized or Depolarized.
  • Conversely, if positive charge is removed from the cell, it becomes more polarized, or hyperpolarized.
  • Finally, if a cell has been depolarized (by adding positive charge), removal of that positive charge will cause the cell to repolarize.

(ii) Depolarization:


Slow & Fast Response Action Potentials: (Speed of the Depolarization)

Fast Responses: Atrial,Ventricular myocardium,His-Purkinje system

Slow Responses: SA node, AV node.

Fast Responses Slow Responses
RMP= -90mV No RMP actually, -65mV
Depolarization by slow K+ influx & then fast K+ efflux. Depolarization by slow Ca+ influx.

No Na+ channel present.

Repolarization by slow K+ efflux & then fast K+ efflux. Repolarization by K+ efflux.
Present in: Atrial,Ventricular myocardium,His-Purkinje system Present in : SA node, AV node.
Gap JN” are more in numbers Gap JN” are less in numbers


Ventricular Hypertrophy:

1.Concentric hypertrophy:-

i.Wall thickened increased

ii.Chamber volume same,due to pressure overload

2.Eccentric hypertrophy:-

i.Little wall thickness increased,due to volume overload

ii.Chmaber volume increased.