College of Veterinary Medicine

Veterinary Clinical Pharmacology Lab

Multidrug Sensitivity in Dogs

MDR1 testingMany herding breed dogs have a genetic predisposition to adverse drug reactions involving over a dozen different drugs. The most serious adverse drug reactions involve several antiparasitic agents (ivermectin, milbemycin and related drugs), the antidiarrheal agent loperamide (Imodium), and several anticancer drugs (vincristine, doxorubicin, others). These drug sensitivities result from a mutation in the multidrug resistance gene (MDR1 gene). At Washington State University's College of Veterinary Medicine you can test your dog for multidrug sensitivity and prevent serious adverse drug reactions. We can work with your dog’s veterinarian to find appropriate drug doses or alternative drugs for your dog based on results of MDR1 testing.

The Partnership for Preventive Healthcare, is an initiative jointly sponsored by the American Animal Hospital Association and the American Veterinary Medical Association. Together the two associations offer a set of Canine and Feline Preventive Healthcare Guidelines. One of the important recommendations is that dog owners use genetic testing—like the MDR1 test —as part of an overall healthcare plan for their pets.

Pricing Information


$60 (US) per dog for tests paid online by credit card

$70 (US) per dog for tests paid by check
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$60 (US) per dog for 5 or more tests submitted at one time in the same package
Dogs, especially those with the MDR1 mutation, should not be given large animal formulations that contain ivermectin, selamectin, moxidectin, milbemycin or related drugs except under the direct supervision of a veterinarian. Severe neurological toxicity can result. FDA approved small animal formulations containing these drugs contain much lower doses and have been tested for safety by the manufacturer.
Veterinary Clinical Pharmacology Laboratory PO Box 609 , Washington State University, Pullman WA 99163-0609, 509-335-3745, Contact Us Safety Links 
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