ICVA Feline Pharmacology and Toxicology 3 — Questions and Answers
Question 1: Which household plant toxin found in lilies (Lilium spp.) causes acute kidney injury in cats?
- Taxine
- Cardiac glycosides
- Unknown nephrotoxic principle (Correct answer)
- Oxalate crystals
Correct answer: Unknown nephrotoxic principle
True lilies (Lilium and Hemerocallis species) contain an unidentified nephrotoxin that causes severe acute tubular necrosis in cats, with even small exposures being potentially fatal.
Question 2: What is the primary mechanism of toxicity when a cat ingests ethylene glycol?
- Direct CNS depression
- Metabolite oxalic acid causes renal tubular calcium oxalate crystal deposition (Correct answer)
- Hemolysis due to oxidative damage
- Hepatic necrosis from reactive intermediates
Correct answer: Metabolite oxalic acid causes renal tubular calcium oxalate crystal deposition
Ethylene glycol is metabolized to glycolic acid and then oxalic acid, which precipitates as calcium oxalate crystals in renal tubules causing acute kidney failure.
Question 3: Which drug is the antidote for ethylene glycol toxicosis and must be given very early in cats (within 3 hours)?
- N-acetylcysteine
- Fomepizole (4-MP) (Correct answer)
- Atipamezole
- Sodium bicarbonate
Correct answer: Fomepizole (4-MP)
Fomepizole (4-methylpyrazole) inhibits alcohol dehydrogenase preventing toxic metabolite formation, but must be administered within 3 hours in cats due to rapid metabolism.
Question 4: A cat presents with tremors, ataxia, and hyperthermia after ingesting a small amount of tea tree oil. What is the mechanism?
- Organophosphate inhibition of acetylcholinesterase
- Terpene compounds causing CNS excitation and dermal absorption toxicity (Correct answer)
- Mycotoxin binding to GABA receptors
- Cardiac glycoside Na/K-ATPase inhibition
Correct answer: Terpene compounds causing CNS excitation and dermal absorption toxicity
Tea tree oil terpenes are rapidly absorbed dermally and orally in cats, causing CNS depression, ataxia, and hepatotoxicity due to deficient feline detoxification pathways.
Question 5: Which drug class requires dose reduction in cats with hepatic disease due to extensive hepatic metabolism?
- Aminoglycosides
- Benzodiazepines (Correct answer)
- Fluoroquinolones
- Penicillins
Correct answer: Benzodiazepines
Benzodiazepines are extensively hepatically metabolized; cats with liver disease show prolonged sedation and can develop hepatic encephalopathy-like signs if doses are not reduced.
Question 6: What is the maximum recommended dose frequency for meloxicam in cats with chronic musculoskeletal pain in Europe, where it is labeled for long-term use?
- Every 8 hours
- Every 12 hours
- Once daily at the lowest effective dose (Correct answer)
- Every 48 hours
Correct answer: Once daily at the lowest effective dose
In Europe, meloxicam is approved for long-term use in cats at the lowest effective dose given once daily, with regular monitoring of renal function.
Question 7: Which rodenticide toxicosis in cats causes signs of hemorrhage and requires vitamin K1 therapy for weeks?
- Bromethalin
- Zinc phosphide
- Anticoagulant rodenticides (second-generation) (Correct answer)
- Strychnine
Correct answer: Anticoagulant rodenticides (second-generation)
Second-generation anticoagulant rodenticides (bromadiolone, brodifacoum) inhibit vitamin K epoxide reductase, requiring 4–6 weeks of vitamin K1 supplementation due to their long half-life.
ICVA Feline Pharmacology and Toxicology 3
Which household plant toxin found in lilies (Lilium spp.) causes acute kidney injury in cats?