“White feet, do not treat”
For pet parents of certain breeds, that saying may be familiar. If not, it most likely is for the veterinarians who care for their dogs. It represents the cautionary guidelines vets often use when deciding whether to prescribe common heartworm medication to certain breeds.
A “mutant gene” is responsible for causing adverse reactions
More than 10 years ago, a gene known as MDR1 was identified in a small number of breeds who often have white feet. The gene is an indicator of a potentially fatal reaction to common doses of Ivermectin, the active ingredient found in heartworm medication, most commonly known as Heartgard.
The MDR1 gene is most often found in collies, aussies, long haired whippets and silken windhounds. Originally thought to be limited to herding dogs, continued research has expanded the list to include some mixed breeds as well.
An affordable test is available to check for the gene
Katrina Mealy, a veterinarian working at Washington State University, was responsible for isolating the gene in 2001. Presence of the gene indicates a potentially fatal reaction not just to ivermectin, but to some other commonly prescribed drugs as well.
Mealy’s continued research on the gene uncovered a growing list of breeds which may harbor the mutation. She also developed a test for the gene, which was patented by WSU in 2004. The test consists of a cheek swab that is sent back to a lab for analysis. The test will reveal the presence or absence of the MDR1 gene for a particular dog.
The test is available through your veterinarian, or directly from WSU. When ordering from WSU, payment is required when the test kit is returned for analysis.
Should you test your dog?
If you have a herding dog, or a herding dog mix, and are concerned about heartworm, it’s not a bad idea to consider this inexpensive test. Talk to your vet about it or read a bit more at the WSU site linked below.
While it can be deadly, heartworm is not a common a problem in much of the country. Every pet parent should consider whether the potential risk from the disease or the preventative treatment is greater. A chat with your vet and some research should help you make an informed decision.
Below are a few links which present different perspectives on the heartworm debate. Where do you fit in?
Click to be taken to the WSU MDR1 gene test and a list of affected breeds
Click to visit the American Heartworm Society, and visit their sponsors
Click to visit an alternative perspective from Dogs Naturally magazine
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