Pet Insurance Quotes

MDR1 Gene Mutation in Dogs

mdr1 gene mutation in dogs

Multidrug Sensitivity in Dogs

Many herding dog breeds are afflicted with a mutation of the multidrug resistance (mdr1) gene. This gene encodes a protein (P-glycoprotein) that is responsible for removing certain drugs and toxins from the brain.

Dogs that carry the mdr1 genetic defect cannot rid their brains of the problem drugs. The result is a neurotoxic buildup that can cause abnormal neurological symptoms and/or death. Research has shown that three of every four Collies have at least one copy of the mutated gene.

There is now a test available to screen for the presence of the mutated mdr1 gene.

Drugs to Avoid for Dogs with MDR1

Drugs to avoid in dogs with the MDR1 gene mutation: The tranquilizer acepromazine; a pain medication called butorphanol; the anti-cancer drugs doxorubicin, vinblastine and vincristine; the antibiotics erythromycin and rifampin; anti-parasitic drugs such as ivermectin (in high doses), milbemycin, moxidectin and selamectin; and the anti-diarrheal drug loperamide (Imodium).

Affected Breeds

Here is a list of dog breeds most susceptible to MDR1 gene mutation.


You can test your dog with at an-home oral swab or take your pup to the vet. Either way, the test will determine if your dog is susceptible.

Cover Your Dog Today



Related Content

Get Free Quotes!

Compare Plans and Prices from the Top Companies