What is the most widely used parasiticide in laboratory animal medicine?

• A. Sulfa
• B. Penicillin
• C. Amitraz
• D. Ivermectin

Answer: (D)

The main idea is that a single medication with broad activity against many parasites, easy to use in several lab species, is highly valued for routine parasite control. Ivermectin fits that role because it is effective against a wide range of parasites, including common internal nematodes and several ectoparasites such as mites and lice. Its action targets receptors in invertebrate nerve and muscle cells, causing paralysis and death, while mammals are less affected at standard, recommended doses, giving a favorable safety profile.

This combination—broad spectrum, practicality across species (like mice, rats, rabbits, and other lab animals), and multiple easy administration routes (oral, injectable, topical)—is why it’s the go-to choice for routine parasite control in laboratory colonies. The other options aren’t parasiticides used this way in lab animal medicine: antibiotics treat bacteria, and amitraz is a more limited ectoparasiticide with less applicability and more safety concerns in common lab species.