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Heartworm and MDR1

Species: Dog
Breed: 1. Aussie, 2. Lassie
Age: 2-5 years
I rrecently had both dogs genotyped for MDR1 mutation and both are positive. Bella is mutant/mutant, Khodi Normal /mutant. Isabella especially get very sick on heartguard and both are mildly on advantix. Ivermectin, Milbemycin, Selamectin and Moxidectin are all on the list of drug sensitivities for MDR1 positive dogs. What can I use for heart worm prevention?


Online vet, Dr. Marie

Dr. Marie replied:

Ultimately this is a question that needs to be answered by your vet as they are aware of which heartworm medications are the most effective in your area.

However, all of the products that you have mentioned are considered safe for dogs with an MRD1 mutation. Even though they contain a tiny amount of ivermectin or a derivative of ivermectin it has been shown to be extremely safe at the dosages contained in these drugs.

I wrote an article that discusses her these dosages and what is safe for these dogs by with an MDR1 mutation.

What kind of reaction do the dogs have? If dogs are reacting to ivermectin the reaction is usually a neurological one. You can see tremors and twitching and things like that. If that is not what you were seeing then there may be something other than ivermectin sensitivity going on.

Unfortunately, I am not aware of an alternative for you.

Dr. Marie


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Disclaimer: Although Dr. Marie is a qualified veterinarian, the information found on this site is not meant to replace the advice of your own veterinarian. AskAVetQuestion.com and Dr. Marie do not accept any responsibility for any loss, damage, injury, death, or disease which may arise from reliance on information contained on this site. Do not use information found on this site for diagnosing or treating your pet. Anything you read here is for information only.

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Dr. MarieDr. Marie is a veterinarian who practices in a busy animal hospital in Ottawa, Ontario. She created Ask A Vet Question as a resource for good, accurate veterinary advice online. Dr. Marie treats dogs, cats, hamsters, guinea pigs, and rats. She has been a vet since 1999.

Is an online vet visit just as good as a trip to your veterinarian? No! But, many times, asking an online veterinarian a question can help save you money. While Dr. Marie can't officially diagnose your pet or prescribe medications, she can often advise you on whether a vet visit is necessary. You can also ask Dr. Marie for a second opinion on your pet's condition.