Original questions written to this exam's published syllabus and pattern. Not past papers.
1. A laboratory validates a new antibody raised against a human protein for use on bovine tissue. Which step is most essential?
Show specific staining in bovine positive controls, with a matched negative control
Skip antigen retrieval entirely, because retrieval causes false positives in bovine tissue
Increase the antibody concentration until all tissue stains
Use only human tissue as the positive control
Answer and working
A. Show specific staining in bovine positive controls, with a matched negative control
Antibodies raised against human or mouse proteins do not always cross-react with the homologous protein of other species, so reactivity must be demonstrated in known positive bovine tissue, with a negative control (primary antibody omitted or replaced) to exclude non-specific staining. Raising concentration increases background, retrieval is often necessary in formalin-fixed tissue, and a human control proves nothing about bovine reactivity.
Veterinary Histology, Embryology & Developmental Anatomy · Histoenzymology and immunocytochemistry
2. One litre of isotonic crystalloid is infused into a normally hydrated animal. Once it has equilibrated, approximately how much remains in the plasma, taking plasma as one-quarter of extracellular fluid?
About 750 mL
About 1,000 mL
About 250 mL
About 83 mL
Answer and working
C. About 250 mL
An isotonic crystalloid distributes through the extracellular fluid, of which plasma is about one-quarter: 1,000 x 0.25 = 250 mL. About 83 mL (1,000 x 1/3 x 1/4) is what stays after 5 per cent dextrose, which behaves as free water and spreads through total body water. 750 mL is the interstitial share.
Veterinary Physiology I: Body Fluids, Blood, Circulation, Respiration and Excretion · Body fluids
3. In a nylon-bag study, a protein supplement has a soluble fraction a = 0.20, a slowly degradable fraction b = 0.60 and a degradation rate c = 0.08 per hour. If rumen outflow rate k is 0.02 per hour, what is the effective degradability using ED = a + bc/(c + k)?
0.80
0.68
0.48
0.32
Answer and working
B. 0.68
ED = 0.20 + (0.60 x 0.08)/(0.08 + 0.02) = 0.20 + 0.048/0.10 = 0.20 + 0.48 = 0.68. Reporting a + b = 0.80 ignores outflow; 0.48 forgets the soluble fraction; 0.32 uses k in the numerator instead of c.
4. A young Quarter Horse foal has weakness, hypoglycaemia and sudden death, and a genetic test confirms a glycogen storage disorder. Which enzyme is most likely deficient?
Glycogen branching enzyme
Glucose-6-phosphatase
Muscle phosphorylase
Acid alpha-glucosidase
Answer and working
A. Glycogen branching enzyme
Glycogen branching enzyme deficiency is an inherited, fatal disorder described in Quarter Horse-related breeds; glycogen lacks normal alpha-1,6 branches. Glucose-6-phosphatase deficiency is human von Gierke disease; muscle phosphorylase deficiency is McArdle disease; acid alpha-glucosidase deficiency is Pompe disease, described in some cattle breeds.
Veterinary Biochemistry · Carbohydrate metabolism
5. Several European countries, notably the Netherlands and the Nordic countries, have moved from blanket to selective dry-cow therapy. The main reason is:
Selective therapy increases milk yield in the next lactation by definition
To reduce antimicrobial use while still treating infected quarters
Teat sealants are banned in these countries
Dry-cow antibiotics are ineffective against all mastitis pathogens
Answer and working
B. To reduce antimicrobial use while still treating infected quarters
Selective dry-cow therapy treats only cows judged infected (for example by SCC history or culture), often with teat sealants for the rest, cutting antimicrobial use as part of stewardship. Teat sealants are widely used, and dry-cow antibiotics do cure many infections.
Livestock Production Management I: General Principles and Ruminants · Care of pregnant and lactating animals
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