Test developed by WSU detects deadly genetic mutation in cats

PULLMAN, Wash. — A new test developed by researchers at Washington State University can detect a rare genetic mutation in cats that can cause potentially deadly reactions to some common medications.

Those medications include those used for flea control and in routine surgeries such as spaying and neutering.

The mutation is found in about 4% of all cats. The only way to tell if a cat has the mutation is through the new genetic test, which pet owners and veterinarians can buy for $60 on WSU’s Veterinary Clinical Pharmacology Laboratory’s website.

“If a cat experiences an adverse drug event that could have been prevented, the veterinary bill will be a lot more than the cost of this test,” said Dr. Katrina Mealey, Regents professor in WSU’s College of Veterinary Medicine.

Mealey and her team had been working since 2014 to develop the test and identify drugs that may be toxic to affected cats, when they discovered the mutation which occurs in the MDR1 (multidrug resistance 1) gene.

Mealey is also responsible for the initial discovery of the MDR1 mutation in dogs in 2001 and for leading the development at WSU of the first commercial tests for canines.

In dogs, Mealey determined the mutation is most frequently seen in herding breeds, but no breed correlation has been identified in cats.

“The mutation is probably about as common in cats as it is dogs, except that in dogs we know it is more breed specific,” Mealey said. “So, if you have a collie, we know the animal has a 75% chance of having the mutation. In cats, though, it seems to be widely distributed and not breed specific.”

Mealey said she recommends the test for all cats.

“Unfortunately, we don’t have a breed association in cats like we do with dogs to be able to say if your cat is this breed, you should get it tested,” she said.

Medications known to cause adverse reactions in cats with the MDR1 mutation include products containing:

• Eprinomectin
• Emodepside
• Ivermectin
• Loperamide
• Selamectin
• Milbemycin
• Moxidectin
• Acepromazine
• Apomorphine
• Butorphanol
• Vincristine
• Vinblastine
• Doxorubicin
• Paclitaxel

Cats with the mutation may have severe reactions to the drugs such as tremors, disorientation, blindness, lack of muscle control, and death.

Once a dog or cat has been tested and then genotyped by WSU, its owner will have online access to a board-certified pharmacologist who can answer questions about the safety of medications.

Mealey and her team are continuing their research to learn which cat breeds are most affected and to identify other medications that may cause negative reactions.

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