We use this opportunity to pass along a really important message to all dog owners, but in particular, certain breeds that include the Australian Shepherd.
There was a time when veterinarians practiced the adage, “white feet, don’t treat” when it came to multi-drug resistance (MDR) defects, or “ivermectin-related” sensitivity. We’ve learned better. The MDR1 mutation affects more than just white footed breeds, and it involves more drugs than ivermectin. MDR1 alterations can also profoundly affect a dog cancer treatments.
Last year, a four year old Australian Shepherd named, “Bristol,” illustrated just how devastating this sensitivity is. Bristol had gone to a facility to try her paw at sheep herding. During the lesson, Bristol, as so many dogs do, found sheep pellets to be a quick and tasty treat. Unbeknownst to Bristol’s owner, the sheep had been recently dewormed with a product containing ivermectin, and the result was dramatic. Bristol was taken to an animal hospital barely responsive and experiencing persistent seizures. Little surprise. Ivermectin crosses the blood-brain barrier and causes neurological damage. Bristol required, and got, immediate and aggressive care, including the assistance of a mechanical ventilator. She began to breathe on her own within 10 days, but she remained unconscious for three weeks. Eventually, she began walking with the assistance of a cart and leg splints, and later began walking under her own power with support from hospital staff. After forty days of treatment, Bristol regained her normal personality traits and the ability to walk, eat and drink on her own. Not every dog has such a happy ending. Talk to your vet about the MDR1 mutation and ivermectin sensitivity.
Image: Australian Shepherd at the Beach by DJ Rogers
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Silken Windhounds have a bit of Sheltie in their make-up and could carry the MDR1 gene. Breeders do a DNA test before making a cross to make sure that they are not breeding one carrier to another.
A terrific warning,Yvonne, thank you for that!
If you have a breed or mix that is possible MDR1 affected, please look at this list of drugs. While Ivermectin is the best known, it is far from the only one or the one with the strongest effect. One that worries me the most is loperamide (one common brand name is Immodium). It is a common over the counter antidiarrheal treatment and it will cause neurotoxicity in dogs that are heterozygous for the mutation as well as those homozygous for it at the standard dose.
https://vcpl.vetmed.wsu.edu/problem-drugs
Karen, your note is much appreciated, and VERY important.
DNA tests for MDR1 are not that expensive, and worth it for your own piece of mind.
You’re so right, Julia, thanks for the reminder!
I have two mixed breed dogs. The first one is nearly 15 and looks like a labrador/pitbull mix, and yes, she does have white feet and a white tip on her tail. She was given Ivermectin when she was a pup and nearly died. Back then we had no DNA tests for this.
Recently I was given another mixed breed dog, and she is OBVIOUSLY mixed with Collie, so the MDR1 test was the first thing I did for her. It’s not expensive and very easy to do, so I do encourage people to invest in it.
Thanks for the input, Guadalupe. Scary business, this ivermectin complication. We’re glad you wrote, there are no better comments than those that come from experienced owners.