NAVLE Veterinary Pharmacology Questions and Answers

Question 1

A veterinarian treats a group of feeder calves for bovine respiratory disease (BRD) with enrofloxacin. What is the primary reason for the strict prohibition of extra-label use of this drug in food-producing animals?

Accepted Answer

It promotes the development of antimicrobial resistance in human pathogens.

Answer

The FDA prohibits the extra-label use of fluoroquinolones like enrofloxacin in food animals primarily to mitigate the risk of promoting antimicrobial resistance. Bacteria such as Salmonella and Campylobacter can develop resistance, which may then be transferred to human populations through the food chain, compromising the efficacy of this critically important class of antibiotics in human medicine.

Question 2

Which of the following antiparasitic drugs has a narrow margin of safety and is associated with severe neurotoxicity in dog breeds with the ABCB1 (formerly MDR1) gene mutation, such as Collies and Australian Shepherds?

Accepted Answer

Ivermectin

Answer

Ivermectin, a macrocyclic lactone, can cause severe neurotoxicity in dogs with the ABCB1/MDR1 gene mutation. This mutation results in a defective P-glycoprotein pump, which is responsible for transporting certain drugs out of the central nervous system. Without a functional pump, ivermectin accumulates in the brain, leading to signs like ataxia, tremors, blindness, and coma.

Question 3

A 4-year-old cat requires post-operative analgesia following a routine ovariohysterectomy. Considering feline-specific metabolism and safety profiles, which of the following NSAIDs is licensed and generally considered a safer short-term option for this patient?

Accepted Answer

Robenacoxib

Answer

Robenacoxib is a COX-2 selective NSAID that is specifically licensed for short-term post-operative pain management in cats. Cats have a deficiency in glucuronyl transferase, an enzyme crucial for metabolizing many NSAIDs, making them highly susceptible to toxicity from drugs like acetaminophen (which is extremely toxic) and phenylbutazone. While carprofen is used in dogs, its use in cats is extra-label and more controversial. Robenacoxib's feline-specific approval and COX-2 selectivity provide a better safety margin.

Question 4

Which of the following medications is a potent, broad-spectrum antiemetic that functions by antagonizing neurokinin-1 (NK-1) receptors in the central vomiting center?

Accepted Answer

Maropitant

Answer

Maropitant is a neurokinin-1 (NK-1) receptor antagonist. It works by blocking the binding of Substance P, a key neurotransmitter in the emetic pathway, at NK-1 receptors located in the vomiting center and the chemoreceptor trigger zone. This mechanism makes it highly effective against vomiting from both central and peripheral stimuli. Ondansetron is a serotonin (5-HT3) antagonist, metoclopramide is primarily a dopamine (D2) antagonist, and famotidine is an H2-receptor antagonist used to reduce stomach acid.

Question 5

A dog is presented with acute onset of severe muscle tremors, hypersalivation, and miosis after potential exposure to a pesticide. Organophosphate toxicity is suspected. Which combination of drugs is the most appropriate treatment to counteract both the muscarinic and nicotinic effects?

Accepted Answer

Atropine and Pralidoxime (2-PAM)

Answer

The standard treatment for organophosphate toxicity involves a combination of Atropine and Pralidoxime (2-PAM). Atropine is a muscarinic antagonist that controls signs like salivation, urination, and bronchoconstriction. Pralidoxime is a cholinesterase reactivator that works to reverse the nicotinic effects, such as muscle tremors and paralysis, by breaking the bond between the organophosphate and the acetylcholinesterase enzyme.

NAVLE - North American Veterinary Licensing Examination Practice Test

NAVLE - North American Veterinary Licensing Examination Practice Test

NAVLE Veterinary Pharmacology Questions and Answers