RCVS Statutory Membership Examination (SME) · UK · Royal College of Veterinary Surgeons
Original practice questions written to the published syllabus · not past papersHow blood, heart, lungs and kidneys keep the internal environment stable in mammals and birds. Acid-base and fluid balance here underpin fluid therapy in the clinic.
In the exams: ICAR AICE-JRF core group 08; ICAR AIEEA-PG 14 (Physiology); PRC 10%; Nepal NLEV 6; China basic paper 13; AVE Paper 1 at least 5
How our questions for RCVS Statutory Membership Examination spread across the units of Veterinary Physiology I: Body Fluids, Blood, Circulation, Respiration and Excretion. Difficulty: 3 easy, 25 medium, 10 hard.
| Acid-base balance | 6 | |
| Haemostasis and coagulation | 5 | |
| Cardiac cycle | 5 | |
| Blood composition and function | 4 | |
| Osmoregulation | 4 | |
| Body fluids | 3 | |
| Renal function | 3 | |
| Control of the cardiovascular system | 2 | |
| Control of respiration | 2 | |
| Gas exchange and transport | 2 | |
| Cellular basis of physiology | 1 | |
| High-altitude physiology | 1 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
An anaemic dog has PCV 20 per cent and 6 per cent reticulocytes. Taking 45 per cent as a normal PCV, what is the corrected reticulocyte percentage?
C. About 2.7 per cent
Corrected % = observed % x patient PCV / normal PCV = 6 x 20 / 45 = 2.67 per cent. Multiplying by 45/20 instead inverts the correction and exaggerates regeneration (13.5 per cent); multiplying by the patient PCV as a fraction (6 x 0.20) without dividing by the normal PCV gives 1.2 per cent. The correction is needed because fewer mature red cells make the reticulocyte share look larger.
Further reading: Harvey JW, Veterinary Hematology: A Diagnostic Guide and Color Atlas.
A nervous Thoroughbred's PCV rises markedly between a sample taken calmly and one taken after it was frightened. The main reason is:
A. Splenic contraction releasing stored red cells under sympathetic stimulation
The equine spleen stores a large red cell reserve that is expelled within minutes under adrenaline, so a single PCV in an excited horse can overstate the red cell mass. Dehydration and erythropoiesis cannot act that fast.
Further reading: Reece WO et al. (eds), Dukes' Physiology of Domestic Animals, 13th ed.
A dog ate an anticoagulant rodenticide 48 hours ago and shows no bleeding yet. Which test is expected to prolong first?
C. Prothrombin time (PT)
The rodenticide blocks vitamin K recycling, and factor VII, measured by the PT, has the shortest half-life, so PT lengthens first; aPTT follows as IX, X and II fall. Bleeding time and platelet count test primary haemostasis, which is not affected.
Further reading: DiBartola SP (ed), Fluid, Electrolyte, and Acid-Base Disorders in Small Animal Practice, 4th ed.
A young male dog has bleeding into joints. Its aPTT is prolonged and its PT and platelet count are normal. The most likely diagnosis is:
C. Haemophilia A
Haemophilia A is X-linked, so affected animals are usually male, and factor VIII sits in the intrinsic pathway, lengthening aPTT but not PT. Rodenticide prolongs PT first; thrombocytopenia lowers the count; von Willebrand disease causes mucosal bleeding with a prolonged bleeding time. Haemophilia A is factor VIII deficiency.
Further reading: Reece WO et al. (eds), Dukes' Physiology of Domestic Animals, 13th ed.
Echocardiography of a dog gives an end-diastolic volume of 60 mL and an end-systolic volume of 20 mL. What is the ejection fraction?
D. About 67 per cent
Stroke volume = 60 - 20 = 40 mL; EF = SV / EDV = 40 / 60 = 66.7 per cent. 33 per cent is ESV/EDV; 300 per cent inverts the ratio (EDV/ESV); 40 is the stroke volume in mL, not a percentage.
Further reading: Reece WO et al. (eds), Dukes' Physiology of Domestic Animals, 13th ed.
On an ECG recorded at 25 mm/s, the R-R interval is 15 mm. What is the heart rate?
C. 100 beats per minute
R-R time = 15 / 25 = 0.6 s; HR = 60 / 0.6 = 100/min. 200 comes from assuming 50 mm/s; 4 comes from dividing 60 by the millimetres; 36 comes from multiplying 0.6 s by 60 instead of dividing.
Further reading: Reece WO et al. (eds), Dukes' Physiology of Domestic Animals, 13th ed.
A dog with a calculated osmolality of 308 mOsm/kg has a measured osmolality of 340 mOsm/kg and was found near spilled radiator fluid. What is the osmolal gap and its meaning?
C. 32 mOsm/kg, suggesting an unmeasured osmole such as ethylene glycol
Osmolal gap = measured - calculated = 340 - 308 = 32 mOsm/kg; adding the two gives 648. A gap this large means an unmeasured solute; ethylene glycol raises it early, before its metabolites cause a high anion gap acidosis. Typical gaps are small, though the reference depends on the laboratory.
Further reading: DiBartola SP (ed), Fluid, Electrolyte, and Acid-Base Disorders in Small Animal Practice, 4th ed.
An anaesthetised dog has pH 7.08, PCO2 70 mmHg and bicarbonate 20 mmol/L. The primary disorder is:
D. Respiratory acidosis
Acidaemia with a high PCO2 points to hypoventilation (6.1 + log10(20 / 2.1) = 7.08). Bicarbonate has not yet risen because renal compensation takes days; a bicarbonate this close to normal does not explain the pH.
Further reading: DiBartola SP (ed), Fluid, Electrolyte, and Acid-Base Disorders in Small Animal Practice, 4th ed.
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