Which analgesic is contraindicated in cats due to risk of severe toxicity?

• A. Buprenorphine
• B. Acetaminophen
• C. Morphine
• D. Meloxicam

Answer: (B)

Acetaminophen is highly toxic to cats because they struggle to detoxify it. Cats have limited capacity to glucuronidate and relatively low stores of glutathione, so when acetaminophen is metabolized by the liver it is converted to a reactive compound (NAPQI). In feline bodies, NAPQI accumulates, depleting glutathione and binding to cellular proteins, causing damage to the liver and red blood cells. This leads to rapid and severe toxicity, including methemoglobinemia (mucous membranes that look bluish/brown), Heinz body formation in red blood cells, vomiting, lethargy, and potentially coma or death. Because even small doses can cause serious harm, acetaminophen is contraindicated in cats. Other options listed have their own considerations but are not inherently contraindicated in cats when used properly (buprenorphine is a common feline analgesic, morphine can be used with caution, and meloxicam requires careful dosing and monitoring).