NAVLE (North American Veterinary Licensing Examination) · USA / Canada · International Council for Veterinary Assessment (ICVA); scored by NBME, delivered by Prometric
Original practice questions written to the published syllabus · not past papersAntibacterial, antifungal, antiprotozoal, anthelmintic, ectoparasiticide and anticancer drugs, and the prudent use that slows antimicrobial resistance.
In the exams: ICAR AIEEA-PG 13 Unit IV (drug resistance); ICAR AICE-JRF core group 07; EAEVE Day One prescribing competences
NAVLE, BCSE, PAVE and ECFVG (North America)
Drug choice for a stated infection and species; species toxicities (lincosamides in horses, enrofloxacin in cats, ivermectin in MDR1 dogs, permethrin in cats, ionophores in horses); 21 CFR 530.41 prohibited extra-label uses; the Veterinary Feed Directive; chemotherapy toxicities.
How our questions for NAVLE spread across the units of Veterinary Chemotherapy & Antimicrobial Stewardship. Difficulty: 10 easy, 37 medium, 6 hard.
| Antifungal drugs | 5 | |
| Anthelmintics | 5 | |
| Anticancer drugs | 5 | |
| Prudent use of antimicrobials | 5 | |
| Sulphonamides | 4 | |
| Beta-lactam antibiotics | 4 | |
| Aminoglycosides | 4 | |
| Macrolides | 4 | |
| Fluoroquinolones | 4 | |
| Antiprotozoal drugs | 4 | |
| Ectoparasiticides | 4 | |
| Tetracyclines | 3 | |
| Mechanisms and problems of drug resistance | 1 | |
| Critically important antimicrobials | 1 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
A Doberman pinscher on trimethoprim-sulphonamide for ten days develops fever and shifting lameness with swollen joints. Which adverse reaction best fits?
C. Idiosyncratic sulphonamide hypersensitivity with polyarthritis
Dobermans are over-represented for immune-mediated sulphonamide reactions: fever, polyarthritis, skin eruptions, thrombocytopenia and hepatopathy. Cartilage erosion belongs to fluoroquinolones in growing animals.
Further reading: Riviere & Papich, Veterinary Pharmacology and Therapeutics, 10th ed.
Why is a Mycoplasma pneumonia not treated with amoxicillin?
A. Mycoplasma has no cell wall for beta-lactams to act on
Lacking peptidoglycan, Mycoplasma is intrinsically resistant to all beta-lactams. Macrolides, tetracyclines, pleuromutilins or fluoroquinolones are used instead.
Further reading: Giguère, Prescott & Dowling, Antimicrobial Therapy in Veterinary Medicine, 5th ed.
Why is once-daily dosing of gentamicin preferred to the same daily dose divided three times?
C. Higher peak improves killing and the long trough reduces kidney uptake
Aminoglycosides are concentration-dependent with a long post-antibiotic effect; a drug-free trough lets proximal tubular cells clear accumulated drug. They are excreted unchanged by the kidney, not metabolised by the liver.
Further reading: Riviere & Papich, Veterinary Pharmacology and Therapeutics, 10th ed.
Why do many regulators discourage systemic gentamicin in cattle even where extra-label use is legal?
D. Kidney residues persist for many months, making withdrawal impractical
Aminoglycosides bind kidney tissue and are eliminated very slowly, so residues persist far beyond the plasma half-life. Carcinogenic residues are the nitrofuran and chloramphenicol concern.
Further reading: Giguère, Prescott & Dowling, Antimicrobial Therapy in Veterinary Medicine, 5th ed.
Enrofloxacin is partly metabolised in most species to which active compound?
C. Ciprofloxacin
De-ethylation of enrofloxacin produces ciprofloxacin, which adds to antibacterial activity.
Further reading: Riviere & Papich, Veterinary Pharmacology and Therapeutics, 10th ed.
A cat becomes acutely blind with diffuse retinal degeneration after a high dose of an antimicrobial. Which drug is most likely?
B. Enrofloxacin
Enrofloxacin at high doses causes dose-related retinal degeneration in cats, linked to a defect in a retinal drug transporter; label limits for cats must be respected.
Further reading: Riviere & Papich, Veterinary Pharmacology and Therapeutics, 10th ed.
In the United States, extra-label use of enrofloxacin in a beef calf is
C. prohibited under 21 CFR 530.41
Fluoroquinolones are on the list of drugs prohibited for extra-label use in food-producing animals. A VFD covers feed use of approved drugs and does not permit extra-label use.
Further reading: 21 CFR 530.41
Several horses die with myocardial necrosis after being fed a cattle ration. Which feed additive is the most likely cause?
C. Monensin
Ionophores such as monensin are extremely toxic to horses, causing cardiac and skeletal muscle necrosis.
Further reading: Riviere & Papich, Veterinary Pharmacology and Therapeutics, 10th ed.
A 400 kg steer is to receive injectable 1% ivermectin at 0.2 mg/kg subcutaneously (a regimen used here for the arithmetic — confirm against the product label and your national formulary). What volume is required?
C. 8 mL
Dose = 0.2 mg/kg x 400 kg = 80 mg. A 1% solution contains 10 mg/mL, so 80 / 10 = 8 mL. 80 mL confuses mg with mL; 20 mL treats the solution as 0.4%; 0.8 mL treats 1% as 100 mg/mL.
Further reading: Calculation
In a dairy herd, selective dry-cow therapy means
C. antimicrobial tubes only for infected cows or quarters, with teat sealant for the rest
Selective dry-cow therapy uses somatic cell counts, culture or history to identify infected cows or quarters for antimicrobial treatment and uses an internal teat sealant in uninfected ones, cutting antimicrobial use without raising new infections.
Further reading: National dairy guidance
Ten here, 53 in the app. The Laisha app has every practice question we have written to NAVLE in this subject, marked as you go, with timed papers, a jump-to-unanswered list and a certificate when you pass at 70 per cent.
Free for ten days, then one subscription of US$10 a month. We would rather say so here than have you find it later.
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