MDR1

If I test one puppy in a litter for the MDR1 genotype do I need to test other puppies?
If I know the MDR1 genotype of the parents, do I need to test the puppies?

Why choose WSU for MDR1 testing Cats and dogs with a mutation in what is known as the MDR1 (multidrug resistance 1) gene can have severe adverse reactions to many common medications, including those frequently used to treat and prevent parasites like heartworms. Fortunately, Washington State University offers accurate genetic testing to determine if your […]

What you need to know about MDR1 testing Some dogs – including as many as 75% of specific herding breeds – and around 4% of all cats have a dangerous mutation in what is known as the MDR1 (multidrug resistance 1) gene, which, if undetected, can lead to severe adverse reactions to many common medications. […]

Since the feline MDR1 mutation was more recently discovered than the canine MDR1 mutation there has been less research on the topic. The WSU PrIMe research team is working to determine if other drugs commonly used for treating cats are substrates for feline P-glycoprotein (i.e., have the potential to cause toxicity in cats with the […]

During her more than two decades at Washington State University, Regents Professor Dr. Katrina Mealey has become a pioneer in veterinary pharmacogenetics and made countless contributions to veterinary medicine, most notably the discovery of a mutation in the MDR1 gene in dogs and cats that can lead to deadly reactions to common medications. The discoveries […]

Learn what medications may be dangerous for your dog with the MDRI genetic mutation. Dogs with the MDR1 genetic mutation can become very ill or die if given certain medications. WSU is the leader in identifying drugs that may be dangerous for dogs with the MDR1 mutation and can identify alternative medications and doses. Once WSU has determined your dog’s […]

What is multidrug sensitivity? Some dogs and cats have a mutation in the MDR1 (multidrug resistance 1) gene also known as the ABCB1 gene, which plays an important role in limiting drug distribution to the brain and in enhancing the excretion of many drugs. Animals with the mutation may have severe adverse reactions – including […]

All heartworm products labeled for dogs in the United States have been tested in dogs with the MDR1 mutation as required by the FDA and have been found to be safe. Drugs such as ivermectin, selamectin, milbemycin, and moxidectin, are commonly used to treat and prevent parasites like heartworms. At low doses, such as those […]

Dogs with a mutation in the MDR1 (multidrug resistance 1) gene may have severe and life-threatening reactions to some common drugs. Research has shown the mutation occurs more frequently in certain breeds. Approximately three of every four collies in the United States have the mutant MDR1 gene. The frequency is about the same in France […]

If you know whether the sire and dam have the mutant MDR1 gene, you can accurately predict if puppies in their litter will have the MDR1 genetic mutation. The chart below details breeding pair combinations and outcomes: