Dogs look to their owners for nutrition, affection, and medical care, so in order to provide the best scenarios of all three, an owner needs to know as much about their pup as possible. Certain breed-specific ailments are easy to spot – an example of this is difficulty breathing in brachycephalic or “smooshed nose” breeds like pugs. Other breed-specific issues in dogs can’t be seen with the naked eye because they lurk in canine genetics, like the MDR1 gene.
What Is The Canine MDR1 Gene?
Unlike some genetic issues, it’s possible for even the most loving and doting dog owner to be completely unaware their dog carries the MDR1 gene until trouble arises. MDR1, which stands for “Multi-Drug Resistance 1”, occurs in a relatively short list of breeds and affects the way a dog’s body processes – or, more accurately, doesn’t process – a variety of canine-targeted medications such as ivermectin, the main ingredient in worming pills. As worming pills are routinely prescribed by vets to treat young dogs and puppies, MDR1 poses a significant health threat to the dog if the owner is unaware their new puppy is a carrier. Like most genetic issues, the most severe reactions will come from a dog that inherited the gene from both of his parents, while a single gene passing on is less worrisome, but still cause for concern.
Why Is The Canine MDR1 Gene Bad?
While the name of the gene itself sounds fairly benign, the issues it causes are far more serious. Rather than simply failing to absorb the “good” parts of medicines like ivermectin, MDR1 keeps the medicine from processing out. If an owner receives a course of worming pills for their puppy, each new dose builds up in the dog’s brain, making him appear more and more ill. Eventually, the result – neurotoxicity – may even be fatal if the problem isn’t discovered in time. Thankfully, veterinary medicine has been aware of MDR1 and the effects of ivermectin on certain affected breeds for nearly 40 years, which means there’s a good chance a vet will catch the potential for MDR1 well before anything’s prescribed.
Which Dog Breeds Carry The MDR1 Gene?
Collies and collie-like breeds are the most susceptible to the MDR1 gene, which can be found in both pedigreed pups as well as, to a lesser degree, collie-mixed breeds. 70% of rough and smooth-breed collies carry at least one copy of the MDR1 gene, followed closely by long-haired whippets (65%) and Australian shepherds (50%), among others with considerably lower percentage rates. Other breeds affected include German shepherds, English sheepdogs, and Shetland sheepdogs. Be aware that even if your dog isn’t a full breed or doesn’t appear to be in the at-risk group, his “mutt” makeup can still contain the MDR1 time-bomb, and finding out the hard way could mean permanent medical injuries – so when in doubt, test!
How Do I Know If My Dog Has The MDR1 Gene?
Genetic tests have become extremely popular for tracing human family trees, but they’re also very useful for tracking down problematic canine genes. Using a blood, buccal (cheek swab), or clipped dewclaw test, there are a variety of testing companies that will provide a full genetic profile of one’s dog, including whether he carries 1, 2, or zero copies of the MDR1 gene in his genetics. These are available as third-party services to curious dog owners, or can often be arranged with a veterinary office for easy collection of testing material.
What Should I Do If My Dog Has The MDR1 Gene?
Owners of commonly-affected breeds are usually advised by canine experts to have their dogs tested immediately (if they haven’t been already). That way, pet parents will be able to make the best medical decisions in the future without compromising the health of their dog. If an at-risk breed dog has already had a negative reaction to certain medications, there’s a very good chance he has at least one copy of the MDR1 gene, if not two.
A canine carrier of the MDR1 gene is approximately 200 times more sensitive to the same medicine dose given to a non-carrier dog, which is why testing is so important. Depending on the results, a trusted vet can recommend an alternative medication course that isn’t harmful to dogs. Owners will also be able to add this crucial information to places like a pup’s tag, collar, or even in his implanted microchip info file. Similar to humans who wear medical alert bracelets, there are medical alert dog tags made of high-visibility materials; these will protect a pooch even if he sneaks out of his home or yard.
The presence of the gene is an undeniable concern for a dog owner, but with a little testing and knowledge, it will never have a chance to negatively affect one’s canine companion. For dog owners, staying informed, remaining proactive in his care, and educating a dog’s medical team will allow pups and their parents to enjoy many happy years playing fetch, walking, and spending quality time without worry.
- “MDR1 FAQs.” ASHGI.org, March 2013, http://www.ashgi.org/home-page/genetics-info/faq/mdr1-faqs. Accessed May 29, 2019.
- Straus, Mary. “Dogs with the MDR1 Mutation: Drug Sensitivities.” Whole Dog Journal.com, November 13, 2012, https://www.whole-dog-journal.com/health/medications/dogs-with-the-mdr1-mutation-drug-sensitivities. Accessed May 29, 2019.
- Geyer, Joachim; Janko, Christina. “Treatment of MDR1 Mutant Dogs with Macrocyclic Lactones.” US National Library of Medicine National Institutes of Health (ncbi.nlm.nih.gov), https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3419875. Accessed May 29, 2019.
- “Multi-Drug Resistance Gene (MDR1).” Animal Genetics.us, (no publish date), https://www.animalgenetics.us/Canine/Genetic_Disease/MDR1.asp. Accessed May 29, 2019.