Researcher recognized for drug reaction discovery in dogs

Mealey with Bumpus
WSU’s Katrina Mealey with her Jack Russell terrier, Bumpus,
named after former Coug football wide receiver, Michael
Bumpus. (Photo by Robert Hubner, WSU Photo Services)

PULLMAN, Wash. – Because one dog’s miracle drug can be another dog’s poison, Washington State University researcher Katrina Mealey has spared countless dogs worldwide from crippling illness and death caused by commonly prescribed medications.

Calling her a “leader in the field of veterinary pharmacogenetics,” the Washington Biotechnology and Biomedical Association will recognize Mealey this week at its Life Science Innovation Northwest conference in Seattle. Mealey, a veterinarian and pharmacologist at WSU’s College of Veterinary Medicine, will receive a 2013 Women to Watch in Life Science Award for identifying why certain dog breeds suffer deadly drug reactions while others do just fine – and then doing something about it.
Drugs turn toxic
In 2001, Mealey discovered a blip in a gene called MDR1 that predisposes herding dogs such as collies, shelties, Australian shepherds and Old English sheepdogs to react violently to a simple deworming pill. Until her discovery, veterinarians were aware that certain breeds – especially collies – were at risk for adverse reactions to the popular drug ivermectin that destroys heartworm, ear mites and numerous other parasites.
Not long after entering the market in the 1980s, ivermectin became known as a super-weapon drug that protects animals and humans alike. But in a sliver of the vast dog world, veterinarians observed that something was amiss. While ivermectin would cure a poodle, it could kill a collie.
Knowing this, “veterinarians followed the adage, ‘White feet, don’t treat,’ but no one knew the ‘why’ behind it,” said Mealey.  “A hereditary component was suspected and so veterinarians wondered if it applied to other breeds as well.”
And it did. Leading a group of WSU researchers, Mealey pinpointed the MDR1 gene and in 2001 published the findings in the journal Pharmacogenics. Since then, she has found 12 other breeds that can carry the faulty gene.
affected breeds
From top: collie, Australian
shepherd, silken windhound.
(Photo display by WSU
College of Veterinary Medicine)

The highest probability is among collies, followed by long-haired whippets, Australian shepherds and silken windhounds. Even mixed breeds can be carriers, said Mealey. (For a full list, go to

It’s also known that these breeds can suffer toxic reactions to other medicines besides ivermectin, including certain cardiac drugs, anti-cancer agents and even the commonly used anti-diarrheal, Imodium.
“The size, colors, coats and other characteristics of these dogs all distinguish them as members of different breeds, appearance-wise,” said Mealey, but the similarity lurks quietly in their DNA.
Whether a large shaggy-haired Old English sheepdog or a small energetic sheltie, if a dog harbors the mutated gene, a standard dose of ivermectin can cause the animal to stagger, convulse and eventually lapse into a coma. A veterinarian not knowledgeable about treatment might well euthanize the dog if it doesn’t die on its own, Mealey explained.
And now, a test
To stop seemingly harmless drugs from killing a subgroup of man’s best friend, Mealey invented an easy-to-do cheek swab test that determines whether a specific dog carries the altered DNA.  In 2004, WSU patented it.
Today, the university distributes the diagnostic test throughout the United States and has licensed labs in Europe and Australia. It is also working closely with a laboratory in South Africa to establish testing on the African continent, said Mealey.
“Our test determines whether these drugs are potentially dangerous for the dog before they can ever be administered,” she said.
Dog love
Sometimes a well-meaning veterinarian will prescribe one of the risky drugs, unaware of the breed’s predisposition, said Mealey. Such was the case for Ginger, an Australian shepherd-golden retriever mix that was given ivermectin for ear mites and later started drooling, became disoriented and couldn’t walk. Her owners, who lived in another state, learned of Mealey’s research on the Internet and contacted her for help.
“I talked to them on the phone every day,” Mealey recalled. “I told them that if dogs get treatment and are nursed through it, they can survive without permanent neurological problems. It can be a long and scary process but they can get through it.”
The owners posted a video of Ginger’s treatment ordeal – and her ultimate recovery – on YouTube. Watching her tail beat like a banner as she romps across a green lawn is a reminder that, while most of us don’t need dogs for herding anymore, we do indeed need them for friendship.
“I spend a lot of time working with pipettes in a lab,” said Mealey, “but the real reward comes from seeing how my work impacts the people who love these dogs.”
To see the YouTube video, go to