Here's a recent column that might be of interest to owners of collie and other herding breeds.
Good news: There is now a genetic test that can identify dogs that are at risk for ivermectin sensitivity, which can be life-threatening.
Bad news: Dogs with this gene are also at risk for reacting to dozens of commonly used medications.
Gene can be fatal for herding dogs
Denise Flaim
Animal House
July 10, 2006
It's not just ivermectin anymore.
Most dog-savvy people - not to mention their vets - know about the connection between collies and invermectin. These herding dogs have a heritable sensitivity to the anti-parasitic drug, which can overwhelm the blood-brain barrier, causing neurotoxicity, coma and, sometimes, death.
In 2001, veterinarian Katrina Mealey of Washington State University College of Veterinary Medicine in Pullman, Wash., and her team found that ivermectin sensitivity is caused by a mutation in the multi-drug resistance gene (MDR1), which controls a protein that helps pump drugs and toxins out of the brain.
But as the research continued, the scientists discovered that the gene may react to more than 50 drugs, such as Loperamide (the over-the-counter antidiarrheal Imodium); the popular tranquilizer Acepromazine, often called "Ace" for short; the heart drug Digoxin; pain-control medication Butorphanol; Cyclosporin, an immunosuppressant used in allergy treaments; and several chemotherapy drugs, including Doxorubicin, Vincristine and Vinblastine.
(For a list of other drugs that have the potential to cause problems in dogs with the MDR1 mutation, visit www.vet med.wsu.edu/depts-VCPL.)
While collies (left) have the biggest issue with this multi-drug sensitivity - about 75 percent of them worldwide carry the defective gene - other herding breeds also are potential victims. Approximately 10 percent of Shetland sheepdogs and Australian shepherds carry the mutant gene. At the opposite end of the spectrum are border collies (below), with only 1 percent believed to be carriers. Mealey says Old English sheepdogs and German shepherds have a "very low" risk factor, with single-digit carrier rates, although white-factor shepherds - those that are albinos or produce it in offspring - are at higher risk.
There is a noninvasive test to determine whether a dog is a MDR1 carrier. The $60 test involves swiping the inside of the dog's cheek with a small bristle brush and mailing the DNA in for analysis.
While Mealey's research has been published in several veterinary journals, she says she still fields calls every week from owners whose vets know nothing about this herding-dog-specific sensitivity.
Ironically, the most well-known source of canine exposure to ivermectin - heartworm medications such as Heartgard - poses the least risk for MDR1 dogs. Mealey notes that the ivermectin dose in heartworm preventives is so low - usually 6 micrograms per kilogram - "that they are safe once a month, even for dogs with the mutation."
By contrast, when ivermectin is used as a treatment for mange, the typical dose is 300 micrograms per kilogram a day - more than 50 times the heartworm dose. "That dog will go into a coma" if it has the MDR1 gene, Mealey warns.
Another area for concern is avermectins used as pesticide sprays. Mealey recalls a case where a couple took their Labrador retriever and collie to their vacation home, where the grounds had been treated with the ivermectin-like compound.
"A day later, the collie was in a coma and the Lab was fine," she explains. "The veterinarians almost euthanized the dog, thinking it was some bizarre neurological thing. If you're a sensitive dog, the coma can last for weeks until the drug gets out of your system," Mealey says - a likely death sentence for dogs that have not been properly diagnosed.
Thankfully, the owners' Web surfing turned up the chemical culprit, and after several weeks, the collie emerged from the coma no worse for wear.
Mealey notes that many specialist vets, such as dermatologists treating mange, will recommend that owners of herding breeds conduct the DNA test to see if the dog has the mutation. "Now a lot of oncologists are starting to as well," she adds, because some cancer-fighting agents will cause a similar reaction in high doses. "When you lower the dose of chemo, it decreases the chances of putting a dog into remission" - a precaution that defeats the purpose of the cancer treatment in the first place.
While some sighthounds such as the silken windhound and long-haired whippet also carry the renegade MDR1 gene, researchers have concluded that the mutation likely found its way into those gene pools through sheepdog crosses made to produce their flowing coats.
As for the gene itself, DNA sequencing of neighboring genes has shown it was a spontaneous mutation that arose in one dog who likely lived in Great Britain in the mid-1800s, before the first herding breeds were even recognized.
This nameless prototypical sheepdog "was a working dog, and probably a good one," Healey explains, " so its genes were passed on" - for better and worse.
Write to Denise Flaim, c/o Newsday, 235 Pinelawn Rd., Melville, NY 11747-4250; or e-mail denise.flaim@newsday.com. For previous columns, www.newsday.com/animalhouse.
Copyright 2006 Newsday Inc.
Comments (16)
Thank you for posting this extremely informative article. We have a white collie and, although we are acutely aware of the heart worm medication dilemma, had no idea about pain medicine, cardiac meds, etc. I've already faxed the article to my vet and I'm assuming he's aware. Needless to say, we'll be running the test on "Awmee". Thank you again, Denise.
our dog lani just had this injection for possible mites. It put her into convulsions and we had to put her to sleep two days ago. What I find interesting is that I was able to find out how deadly this medication is to herding dogs but the vet knew nothing of the simple blood test and swab to check for the gene. I am also finding out that MANY vets know nothing of this. We have lost our friend and family member and we are heartbroken. How do we keep others from going through this? Why isn't it widely known to vets about this test?
thank you,
sandra larson and al schlette
Sandra and Al - I am so sorry for your loss. It is sad to lose any fur baby, but when you are trying to do something good for them and something like this happens it is indeed heartbreaking.
May I suggest something. I would research this situation and get all the info possible. Then I would make a website in honor of your baby, with the story of your loss and the information to help others not experience this.
If you want to do this, I love doing web design. I would be happy to do the website for you free of charge if you purchase a domain site for it. It would be my honor in memory of your Lani.
We need to get the word out there for others if the vets will not!
God bless you in your loss.
thank you kathleen. The website is a wonderful idea. I know nothing of how to design one but perhaps will take you up on your offer. I will discuss with Al and let you know. Do you have a personal email address? We want to do something for our dear Lani - so that others do not have to go through this. We are so very sad and disappointed. she was a wonderful loving dog that we rescued from an animal shelter. She was only 9 months old. Thank you for your concern and return email.
Sandra
We own a blue heeler/border collie mix. Two nights ago we gave her Frontline Plus. Ever since she has been incredibly thirsty, showing signs of tremor and is scary lethargic. We had given this before but I don't recall there being a problem. I wonder if this is somehow related. I am taking her to the vet tomorrow and am glad that this information in online.
Shari, did you give her a chewable kind. If you did, I have been hearing that some of the chewable heartworm medicines are showing the same symptoms in pets as those who ate the tainted pet food. I would discuss this with your vet and have a blood panel done.
Some collies and Border collies are very, very sensitive to heartworm treatments especially Ivermectin,and pyrethrin and other flea treatments- and like Meri-lou said it can cause liver damage and that is what the tainted dog food is causing, in part. Get your dog to the vet today.
Pam and Kathy thise was posted under one of the other topics -
We own a blue heeler/border collie mix. Two nights ago we gave her Frontline Plus. Ever since she has been incredibly thirsty, showing signs of tremor and is scary lethargic. We had given this before but I don't recall there being a problem. I wonder if this is somehow related. I am taking her to the vet tomorrow and am glad that this information in online.
Posted by: Shari | May 02, 2007 at 04:36 AM
Shari, did you give her a chewable kind. If you did, I have been hearing that some of the chewable heartworm medicines are showing the same symptoms in pets as those who ate the tainted pet food. I would discuss this with your vet and have a blood panel done.
Posted by: Meri-Lou | May 02, 2007 at 10:26 AM
Some collies and Border collies are very, very sensitive to heartworm treatments especially Ivermectin,and pyrethrin and other flea treatments- and like Meri-lou said it can cause liver damage and that is what the tainted dog food is causing, in part. Get your dog to the vet today.
Posted by: Karen | May 02, 2007 at 10:56 AM
Research was also going on here in Germany at the University of Gießen. There was a study in 2004, where I took part and got the information that my Rough Collie is affected by this gene defect.
I started to inform myself, knowing very soon that Ivermectin would only be the tip of the iceberg and that this serious mutation should be heeded in breeding plans. There should be no more dog being borne with this defect!
Therefore we build the homepage www.mdr1-defekt.de, which we also provide in English and some other languages. Here we inform about the MDR1 gene defect and show tested dogs. We are a place where breeders can get in contact and where all can find a dog which is not affected - this because we also inform about litters, where no affected puppie will be.
And we do not only show german dogs but dogs from all over the world. And we would like to show your dogs, too.
For more informations please look here: http://www.mdr1-defekt.de/index.php?lang=EN
Kind regards,
Kris, Germany
www.mdr1-defekt.de
Kris,
If you'll look at the right hand side of this blog, you'll see the most recent blogs. This one is almost a year old. I think everyone would be interested in hearing what you have to say. "Tennessee Pete" is fairly current.
My dog went in for its first shots at 7 weeks and has had a very severe reaction to the ivermectin. The puppy is now better but is left blind and deaf. Does anyone know if its sight or hearing will return over time???
My dog went in for its first shots at 7 weeks and has had a very severe reaction to the ivermectin. The puppy is now better but is left blind and deaf. Does anyone know if its sight or hearing will return over time???
Gabby, I found this on the internet and it may shed some light on what happened to your dog. What breed do you have?
Given that the National Poisons Control Centre is regularly contacted about ivermectin intoxication in dogs, we would like to emphasize the warning of Nap et al. (4) that the use of ivermectin in companion animals, and especially Collies and Bobtails, is not without risk. For this reason, the 'off-label' use of ivermectin for these dogs is not advised. There is currently a wide choice of selective drugs for the treatment of canine parasitic diseases.
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