MDR1 GENE – AUSSIE DRUG TOXICITY
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It is well known that certain breeds have reactions to certain drugs. It was
previously unknown why some dogs were sensitive and some not. Advances in
molecular biology has found the problem to be due to a mutation in the
multi-drug resistant 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 can not pump some drugs out of the brain as a
normal dog would. The result may be illness possibly requiring an extended
hospital stay, or even death. You simply need to use alternative drugs
recommended by you vet that are safe for these breeds.
Infected breeds that have been positively diagnosed include:
Collies (rough and smooth), Shetland Sheepdogs, Australian Shepherds (all
three sizes), Old English Sheepdogs, German Shepherds, McNabbs, Long-Haired
Whippets & Silken Wind hounds and Mix-breeds with any of the above in their
background! As the testing becomes more precise, there may be more breeds
and drugs added to the list.
How common is the MDR1 mutation in Aussies?
32% of the Standard Aussies and 49% of Mini-Aussies have at least one copy of
How do I know if my dog has the MDR1 mutation?
If your dog has already reacted to one of these drugs, it has the mutation.
However, reactions can be so dangerous to your dog it is advisable to have the
dog tested so you know whether it is sensitive before it receives any of the
What do the MDR1 test results mean?
This is a DNA mutation test. It will determine whether or not a dog has the MDR1
mutation and, if it does, whether it has one copy or two. The test report will
provide you with the genotype for your dog, generally listed as Normal/Normal,
Normal/Mutant or Mutant/Mutant.
Dogs with even one copy of the mutation should be considered sensitive to
listed drugs. If your dog carries the mutation, provide a copy of the test results
and a copy of the listed drugs to every veterinarian who treats your dog and let
them know your dog cannot have those drugs.
What dogs should be tested and how often?
Since this is a DNA test, a dog only needs to be tested once. Due to the high
frequency of the mutation in the breed and the variety of drugs to which dogs
with the mutation can react, all dogs, including rescues of unknown parentage
and Aussie-mixes should be tested. Their lives could depend on it.
The only exception is as follows: If both parents of a dog have tested
Normal/Normal, they cannot pass on the gene and their offspring will not need to
be tested. However, if a Normal/Normal dog is bred to one of unknown status or
one that has even a single copy of the mutation, the offspring must be tested.
How do I get the test done?
For those in North America, The test is available through Washington State
University. Information can be found on their website:
In Europe the test is available through Genetic Counseling Services in the
In Australia, Genetic Technologies Ltd. and Gribbles Veterinary Pathology offer
Below is a list of drugs that have been documented, or are strongly suspected to
cause problems in dogs with MDR1 Gene Mutation:
PLEASE PRINT a VET INFO SHEET and DRUG LIST
for Yourself AND Your Vet as a Saftey Precausion.
Click Here for Printable Version
SICKNESS OR EVEN DEATH CAN EASILY BE AVOIDED
STAY AWAY FROM THE FOLLOWING DRUGS OR HAVING YOUR DOG TESTED
BEFORE USING THEM!
*IVERMECTIN (antiparasitic agent)
LOPERAMIDE (Imodium, over the counter human anti-diarrhea agent)
DOXORUBICIN (anti-cancer agent)
VINCRISTINE (anti-cancer agent)
VINBLASTINE (anti-cancer agent)
CYCLOSPORIN (immunosuppressive agent)
DIGOXIN (heart drug)
BUTAPHONAL (pain control)
POTENTIAL PROBLEM DRUG
Click to Learn More About The MDR1 Gene
** Please share this information with other owners of affected breeds! **