MDR1 DRUG SENSITIVITY

What Drives Us

One in two Australian Shepherds carry at least one copy of this gene mutation.  MDR1 is the abbreviated name of a gene called Multi-Drug Resistance 1.  A mutation of this gene causes sensitivity to Ivermectin and a number of other drugs.  Dogs with the mutation will react to those drugs.   Whether a dog reacts depends on the dosage of the drug.  A dog may not react to very low doses, as with the amount of Ivermectin found in heart worm products.  Typical doses of a variety of medications will cause reactions in dogs with two copies of the mutation, but some drugs – most notably several chemotherapy agents – can cause reactions in dogs with only one.   This mutation is considered a fault, but not a disqualification for breeding.  At Best Friend Aussies, we do not breed two dogs that are both carriers.  Rosey has just one copy of the gene and is considered a carrier.  Rowan is clear.  So, there is a 50% chance that their puppies will carry just one copy.  A simple genetic test can be performed by your veterinarian to see if your puppy is a carrier.  Otherwise, it is best to avoid giving Ivermectin type deworming medication to your dog.  Your Veterinarian will know based on your dogs breed, not to prescribe any of the other potentially harmful drugs.