Is Your Dog On The List? These Dog Breeds Carry A Potentially Fatal Ge - World of Angus

Is Your Dog On The List? These Dog Breeds Carry A Potentially Fatal Gene

The MDR1 gene stands for Multi-Drug Resistance Gene. It was discovered by Washington State University. MDR1 codes for a protein that is supposed to protect the brain by moving potentially dangerous chemicals away from the brain. When a dog has the mutation, the MDR1 gene causes reactions to a variety of drugs from antibiotics to cancer treatment.


These drugs include:

  • Acepromazine
  • Butorphanol
  • Doxorubicin
  • Doramectin
  • Emodepside
  • Erythromycin
  • Ivermectin
  • Loperamide
  • Milbemycin
  • Moxidectin
  • Paclitaxel
  • Rifampin
  • Selamectin
  • Vinblastine
  • Vincristine

The defective protein prevents dogs ability to clear out certain drugs from the brain. The buildup of these drugs leads to a build up of toxins. It can causes neurological issues such as seizures, ataxia and death.

It can appear in mixed breed dogs. For example, even if you have a dog that's only part Australian Shepherd, your dog could still have the gene. It is also very popular in herding breed dogs like Australian Cattle Dogs.

The most affected breeds are:

  • Australian Shepherd
  • Australian Shepherd, Mini
  • Border Collie
  • Collie
  • English Shepherd
  • German Shepherd
  • Herding Breed Cross
  • Long-haired Whippet 
  • McNab
  • Mixed Breed
  • Old English Sheepdog
  • Shetland Sheepdog
  • Silken Windhound

Fear not! Your vet can test for the MDR1 gene and make educated treatment choices for your dog. If your dog is positive, always let any new vet know about the gene. 


1. Animal Genetics 2. Wisdom Panel

Nicole Simone
Nicole Simone


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