Penicillin is the best antibiotic to treat mice, rats, hamsters, and guinea pigs.

• A. True
• B. False
• C. Depends on the pathogen
• D. Only under supervision

Answer: (B)

Antibiotic choice is built on the pathogen involved and the specific animal species, not on one drug being universally best. In small mammals, there isn’t a single antibiotic that works best for all four species. Guinea pigs and hamsters are hindgut fermenters with a gut microbiota that is crucial to their health; penicillin can disrupt that balance so severely that it can cause life-threatening enteritis. Because of this sensitivity, penicillin is often avoided in these species. Even for mice and rats, penicillin isn’t automatically the optimal choice—the best drug depends on what organism is causing the infection, how the drug is absorbed and distributed in that species, and potential toxicity. So the idea that penicillin is the best antibiotic for all these animals isn’t correct; treatment needs to be tailored to the pathogen and the animal.