IAS (Civil Services) Exam 2009

Answered Question paper

Animal Husbandry & Veterinary Science Paper – II

Section ‘A’

1. Write precisely on any three of the following in about 200 words each:   3X20=60

  1. Anatomical differentiation between foetal and adult circulation; and BLASTOCYST and BLASTODISC.

  2. Adult circulation

    • Non-oxygenated blood enters the right atrium via the inferior and superior vena cava.
    • Increase level of blood in the right atrium causes the tricuspid valve to open and drain the blood to the right ventricle.
    • Pressure of blood in the right ventricle causes the pulmonic valve to open and non-oxygenated blood is directed to the pulmonary artery then to the lungs.
    • Exchange of gases occurs in the lungs. Highly oxygenated blood is returned to the heart via the pulmonary vein to the left atrium.
    • From the left atrium the pressure of the oxygenated blood causes the mitral valve to open and drain the oxygenated blood to the left ventricle.
    • Left ventricle then pumps the oxygenated blood that opens the aortic valve. Blood is then directed to the ascending and descending aorta to be distributed in the systemic circulation.

    Fetal Circulation

    • Exchange of gases occurs in the placenta. Oxygenated blood is carried by the umbilical vein towards the fetal heart.
    • The ductus venosus directs part of the blood flow from the umbilical vein away from the fetal liver (filtration of the blood by the liver is unnecessary during the fetal life) and directly to the inferior vena cava.
    • Blood from the ductus venosus enters to the inferior vena cava. Increase levels of oxygenated blood flows into the right atrium.
    • In adults, the increase pressure of the right atrium causes the tricuspid valve to open thus, draining the blood into the right ventricle. However, in fetal circulation most of the blood in the right atrium is directed by the foramen ovale (opening between the two atria) to the left atrium.
    • The blood then flows to the left atrium to the left ventricle going to the aorta. Majority of the blood in the ascending aorta goes to the brain, heart, head and upper body.
    • The portion of the blood that drained into the right ventricle passes to the pulmonary artery.
    • The umbilical arteries then carry the non-oxygenated blood away from the heart to the placenta for oxygenation.


    Difference between Adult and Foetal Circulation
    Criteria Adult Circulation Foetal Circulation
    Artery Carries oxygenated blood away from the heart Carries Non-oxygenated blood away from the fetal heart
    Veins Carries non-oxygenated blood towards the heart Carries oxygenated blood back to the heart
    Exchange of Gases Takes places in the lungs Takes place in the placenta
    Pressure Increase pressure on the left side of the heart Increase pressure on the right side of the heart



    fetalcirculation


    BLASTOCYST

    • The blastocyst is a structure formed in the early development of mammals. It possesses an inner cell mass (ICM) which subsequently forms the embryo. The outer layer of the blastocyst consists of cells collectively called the trophoblast. This layer surrounds the inner cell mass and a fluid-filled cavity known as the blastocoele. The trophoblast gives rise to the placenta.
    • The use of blastocysts in in-vitro fertilization (IVF) involves culturing a fertilized egg for five days before implanting it into the uterus. It can be a more viable method of fertility treatment than traditional IVF. The inner cell mass of blastocysts is also a source of embryonic stem cells.

    blastocyst

    BLASTODISC

    • In eggs of reptiles and birds, the clear cytoplasm is concentrated at one pole called the blastodisc.
    • Blastodisk – the disk of cells formed during cleavage that lies on top of the yolk of large-yolked eggs of fishes, reptiles and birds, and on the top of the yolk sac of mammals

  3. Pharmacological role of ANTICHOLINERGIC agents.

  4.  An anticholinergic agent is a substance that blocks the neurotransmitter acetylcholine in the central and the peripheral nervous system. These agents inhibit parasympathetic nerve impulses by selectively blocking the binding of the neurotransmitter acetylcholine to its receptor in nerve cells. Anticholinergics are divided into three categories in accordance with their specific targets in the central and peripheral nervous system: antimuscarinic agents, ganglionic blockers, and neuromuscular blockers.

    Pharmacology role is as follows:

    • An anticholinergic agent is a substance which blocks the neurotransmitter Acetylcholine in the CNS and PNS. Classic example is Atropin.
    • Atropine is specific antagonist for muscarinic receptors. It is competitive inhibitor.
    • Antropine is selective for nicotinic and muscarinic receptors.
    • Anticholinergics are administered to reduce the effects mediated by acetylcholine on acetylcholine receptors in neurons through competitive inhibition. Therefore, their effects are reversible.
    • A parasympatholytic element, also referred to as anticholinergics, reduces the activity of the parasympathetic nervous system.
    • The term parasympatholytic typically refers to the effect of a drug, although some poisons, such as organophosphates act to block the parasympathetic nervous system as well.

  5. Clinical manifestations, diagnosis and treatment of copper and CYANOGENIC glycoside toxicosis.

  6. Copper toxicosis:
     Many factors that alter copper metabolism influence chronic copper poisoning by enhancing the absorption or retention of copper. Low levels of molybdenum or sulfate in the diet are important examples.
    Primary chronic poisoning is seen most commonly in sheep when excessive amounts of copper are ingested over a prolonged period. The toxicosis remains subclinical until the copper that is stored in the liver is released in massive amounts. Increased liver enzymes may provide an early warning of the pending crisis. Blood copper concentrations increase suddenly, causing lipid peroxidation and intravascular hemolysis. The hemolytic crisis may be precipitated by many factors, including transportation, handling, weather conditions, pregnancy, lactation, strenuous exercise, or a deteriorating plane of nutrition.

    Clinical Findings:
     Acute copper poisoning causes severe gastroenteritis characterized by abdominal pain, diarrhea, anorexia, dehydration, and shock. Hemolysis and hemoglobinuria may develop after 3 days if the animal survives the GI disturbances.

     The sudden onset of clinical signs in chronic copper poisoning is associated with the hemolytic crisis. The time of onset is influenced by the concentration of copper in the diet. Signs in affected animals include depression, lethargy, weakness, recumbency, rumen stasis, anorexia, thirst, dyspnea, pale mucous membranes, hemoglobinuria, and jaundice. Several days or weeks before the hemolytic crisis, liver enzymes, including ALT and AST, are usually increased. During the hemolytic crisis, methemoglobinemia, hemoglobinemia, and decreases in PCV and blood glutathione are usually seen. In camelid species such as alpacas or llamas, no hemolytic crisis is seen, although extensive liver necrosis remains a consistent manifestation.
    Animals that survive the acute episode may die of subsequent renal failure. Photosensitization may occur in association with chronic copper poisoning, reflecting the hepatotoxicity common to both syndromes. Cirrhosis of the liver is also associated with the syndrome in dogs.

    Treatment:
     Often, treatment is not successful. The prognosis is poor in all species. GI sedatives and symptomatic treatment for shock may be useful in acute toxicity. Penicillamine (50 mg/kg/day, PO, for 6 days) or calcium versenate may be useful if administered in the early stages of disease to enhance copper excretion. Vitamin C (500 mg/day/sheep, SC) has been shown to reduce oxidative damage to RBCs during the hemolytic crisis. Ammonium tetrathiomolybdate (1.7 mg/kg, IV, every other day for 6 days) is effective for the treatment and prevention of copper poisoning. This treatment, which reduces copper absorption and enhances copper elimination, should be used conservatively. A withdrawal period of ~10 days is required for this medication.


    CYANOGENIC glycoside toxicosis:

    [If you know the answer, please comment below or mail us at gnanadeevige@gmail.com ]


  7. Zero Disease concept and CHEMOPROPHYLAXIS.

  8. Zero Disease concept

    • Absence of disease in animal population or a flock mean zero disease. The base situation of no disease.
    • To estimate the losses caused by a disease. It is necessary for initiating the research or measures to develop vaccine/ drug to control or eradicate a disease. However, there is hardly any estimate about potential cost of reaching the zero disease status once the disease is there. Moreover, there is hardly any flock, free of all disease.
    • Alternate method to zero disease concept: Productivity estimates associated with disease control/ elimination from a specific flock can be applied to estimate the cost of control/ eradication.
    • It have several limits as no knowledge of disease, no control programme ever initiated, no estimates have been made, requires too many parameters to be recorded.

    CHEMOPROPHYLAXIS

    • Chemoprevention (also Chemoprophylaxis) refers to the administration of a medication for the purpose of preventing disease or infection.
    • In some cases, chemoprophylaxis is initiated to prevent the spread of an existing infection in an individual to a new organ system, as when intrathecal chemotherapy is administered in patients with malignancy to prevent further infection.
    • Using chemoprophylaxis as a treatment against early signs of tuberculosis has proven to be effective.
    • In familial adenomatous polyposis physicians observed polyps regression with NSAIDs for anti-inflammatory therapy
    • Chemoprophylaxis is also used to treat several different varieties of meningococcal infections for close contact exposure to Neisseria meningitidis