Author: Melissa Boldan, DVM

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In This Article Summary View 6 More +

References Chicoine A. DVM 360. Testing for the MDR1 gene in Collie breeds. 2010. Dockweiler J. Cornell University College of Veterinary Medicine. Drug Sensitivity: MDR1. Mealey K, Meurs K. Breed distribution of the ABCB1-1Delta (multidrug sensitivity) polymorphism among dogs undergoing ABCB1 genotyping. Journal of the American Veterinary Medical Association. 2008. Washington State University. Dog breeds commonly affected by MDR1 mutation. 2021. Featured Image: iStock.com/didesign021      ,References Close,What Is the MDR1 Gene in Dogs? In 2001, a veterinary pharmacologist discovered that several herding-breed dogs were more likely to have a genetic mutation making them more sensitive to certain medications. The MDR1 (multidrug resistance 1) gene mutation causes a change in an important protective molecule called p-glycoprotein, which helps to eliminate medications and other toxic compounds from the dog’s body and prevents these medications from going places they shouldn’t, such as the brain. Dogs with a mutation of the MDR1 gene (or a defective MDR1 gene), also called the ABCB1 gene, are more likely to have serious side effects from certain classes of medication, namely ivermectin, an anti-parasite drug. Many Collie pet parents know that ivermectin drugs may be dangerous for their dog when used at non-FDA approved doses. The MDR1 gene mutation is responsible for this increased risk of toxicity. But it’s not just Collies, and it’s not just ivermectin. Other breeds and medications are linked as well. As we’ve learned more about genetics, we have developed ways to identify dogs that carry the MDR1 gene mutation and to make better choices in reducing their risks of serious medication side effects.

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In This Article Summary View 6 More +