Veterinary Clinical Pharmacology Lab

Multidrug Sensitivity in Dogs

Some dog breeds are more sensitive to certain drugs than other breeds. Collies and related breeds, for instance, can have adverse reactions to drugs such as ivermectin and loperamide (Imodium). At Washington State University's College of Veterinary Medicine you can get your dog tested for drug sensitivity and keep up with the latest research.

Drug sensitivities result from a mutation in the multi-drug resistance gene (MDR1). This gene encodes a protein, P-glycoprotein that is responsible for pumping many drugs and other toxins out of the brain. Dogs with the mutant gene cannot pump some drugs out of the brain as a normal dog would, which may result in abnormal neurologic signs. The result may be an illness requiring an extended hospital stay - or even death.

Test Your Dog

Most Commonly Affected Breeds Australian Shepherd Australian Shepherd (Mini) Collie Long-haired Whippet McNab Silken Windhound Click here for a complete list