VTNE Veterinary Pharmacology 5 — Questions and Answers
Question 1: What is the primary pharmacological effect of dexmedetomidine?
- Mu-opioid receptor agonism causing analgesia and sedation
- Alpha-2 adrenergic receptor agonism causing sedation, analgesia, and muscle relaxation (Correct answer)
- GABA-A receptor potentiation causing sedation
- NMDA receptor antagonism causing dissociation
Correct answer: Alpha-2 adrenergic receptor agonism causing sedation, analgesia, and muscle relaxation
Dexmedetomidine is a highly selective alpha-2 adrenergic agonist that produces dose-dependent sedation, analgesia, and muscle relaxation.
Question 2: Which vaccine adjuvant is most commonly associated with injection-site sarcoma in cats?
- Modified live virus particles
- Aluminum salts (aluminum hydroxide/phosphate) (Correct answer)
- Carbopol polymer
- Oil-in-water emulsions
Correct answer: Aluminum salts (aluminum hydroxide/phosphate)
Aluminum-based adjuvants in killed vaccines are associated with feline injection-site sarcoma (FISS), prompting recommendations to use non-adjuvanted vaccines in cats when possible.
Question 3: A dog on long-term corticosteroid therapy suddenly stops receiving the medication. What is the primary risk?
- Acute liver failure
- Adrenal insufficiency due to HPA axis suppression (Correct answer)
- Hyperthyroidism rebound
- Sudden nephrotoxicity
Correct answer: Adrenal insufficiency due to HPA axis suppression
Prolonged exogenous corticosteroid use suppresses the hypothalamic-pituitary-adrenal (HPA) axis, and abrupt withdrawal can cause life-threatening adrenal insufficiency.
Question 4: Which local anesthetic has the longest duration of action and is commonly used for nerve blocks in large animals?
- Lidocaine
- Procaine
- Bupivacaine (Correct answer)
- Mepivacaine
Correct answer: Bupivacaine
Bupivacaine has the longest duration of action among common local anesthetics (up to 6-8 hours) and is used for prolonged nerve blocks in horses and cattle.
Question 5: What is the antidote for organophosphate toxicity?
- Flumazenil and pralidoxime
- Atropine and pralidoxime (2-PAM) (Correct answer)
- Naloxone and activated charcoal
- N-acetylcysteine and vitamin K1
Correct answer: Atropine and pralidoxime (2-PAM)
Atropine counteracts excessive muscarinic stimulation (SLUDGE signs), while pralidoxime (2-PAM) reactivates acetylcholinesterase if given early before aging occurs.
Question 6: Which antibiotic is bacteriostatic and works by binding the 30S ribosomal subunit to inhibit protein synthesis?
- Amoxicillin
- Enrofloxacin
- Doxycycline (Correct answer)
- Clindamycin
Correct answer: Doxycycline
Doxycycline (a tetracycline) is bacteriostatic and inhibits bacterial protein synthesis by binding the 30S ribosomal subunit, preventing aminoacyl-tRNA binding.
Question 7: A rabbit is being treated for E. cuniculi (Encephalitozoon cuniculi). Which drug is the treatment of choice?
- Metronidazole
- Fenbendazole (Correct answer)
- Praziquantel
- Toltrazuril
Correct answer: Fenbendazole
Fenbendazole is the recommended treatment for E. cuniculi in rabbits, used for 28 days to reduce neurological signs and parasite burden.
VTNE Veterinary Pharmacology 5
What is the primary pharmacological effect of dexmedetomidine?