The use of ivermectin should be avoided or carefully controlled in which group of animals?

• A. Sight hound breeds
• B. Animals weighing less that 40 grams
• C. Albino animals
• D. Rabbits

Answer: (A)

Ivermectin safety in dogs hinges on how well a key transport protein can move the drug out of the brain. In some breeds, especially sight hounds, this transporter (P-glycoprotein, produced by the MDR1 gene) doesn’t work as effectively. When it’s less functional, ivermectin can accumulate in the brain and cause serious nervous-system toxicity at doses that would be okay for most dogs. Because of this breed-specific risk, ivermectin should be avoided or used at very careful, veterinary-supervised levels in sight hounds, with consideration of alternative parasite preventives or MDR1 genetic testing when dosing decisions are made. Watch for neurologic signs such as ataxia, tremors, disorientation, or seizures and seek care immediately if exposure is suspected. The concern here is specific breed genetics in dogs, not factors like size, color, or other species.