Which drug is a short-acting analgesic with less sedative effect, approved for analgesia in horses and dogs?

• A. Pentazocine
• B. Buprenorphine
• C. Methadone
• D. Diphenoxylate

Answer: (A)

Short-acting analgesics with relatively less sedative effect are often mixed opioid receptor agents that provide pain relief without strong central depression. Pentazocine fits this pattern because it acts mainly as a kappa-opioid receptor agonist with only partial activity at mu receptors. This combination yields effective analgesia while producing less sedation and respiratory depression than full mu-agonist opioids, and its duration is shorter than many long-acting options. It is approved for analgesia in both horses and dogs, making it the best choice among the options.

Buprenorphine, by contrast, is a potent, long-acting analgesic that acts as a partial mu agonist with a ceiling effect; its longer duration makes it less of a short-acting option. Methadone is a strong mu-agonist with a relatively long duration of action, contributing to both potent analgesia and longer-lasting effects. Diphenoxylate is primarily an antidiarrheal agent with limited analgesic use in veterinary contexts, not a standard analgesic for horses or dogs.