Ivermectin sensitivity in Collies and related breeds

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sarasomething

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i was researching switching from Heartguard (an Ivermectin-based med) to another heartworm preventative b/c i heard about the possibility of Shelties experiencing more side effects from Ivermectin than non-Collie breeds. Apparently they are also sensitive to other heartworm preventative meds, but the reassuring thing was that they have to receive at least 10 times the recommended dose to have adverse reactions.

i found this paper interesting, if anyone else would like to see it:
Research on Ivermectin reactions in Collies -
http://www.awca.net/ivermectin.pdf

Anyways, I figured I'd also stick with Heartguard, since it supposedly has a higher rate of successfully preventing infection, if it's no more dangerous than other heartworm preventatives.

I live in the south and spend a lot of time out doors with the dog, so year-round treatment is a necessity.
 
While I was researching Shelties before getting one, one of the Sheltie breed books I had also said that Collies and Shelties were senstitive to Ivermectin, and suggested that a better alternative for them was milbemycin oxime (the medicine in Interceptor). The other book I had said nothing about it either way. When we discussed it with our vet, she said that they had changed the formulation of Heartguard slightly so it wasn't really a concern, but Interceptor is still what we ultimately wanted to put Lerwick on, just in case.

However, since our vet doesn't stock Interceptor, we had Lerwick on Heartguard (and maybe even a different brand after that), at first. Our vet could order Interceptor for us, but since Lerwick's weight was changing so rapidly as he grew, there was really no sense in us buying a supply of Interceptor because he would grow out of it too fast. He's finally at the point where we figure that he will be able to stay in one weight bracket for long enough to get a 6 month supply.

Since we live in an area where fleas are also a year-round irritation, we have gotten a 6 month supply of Sentinel, which is Interceptor + flea medication. We'll be giving him his first dose on Nov. 1.

What I like about Sentinel is that it is a tablet. Last time the vet gave us combination heartworm + flea medication, it was a topical gel that we had to put on the back of his neck. I did my best to part the hair and get the gel right on the skin, as per instructions, but I felt like most of it just ran into his fur, and I was just not satisfied that he was getting the full benefits of the medication. And, of course, the medicine stayed in his fur and stank for days. If you touched his fur where the medicine was, it would come off on your fingers. So gross, and again, I felt like he wasn't getting the full benefit of the medicine, since it seemed to be rubbing off awfully easily.
 
15 years ago, when I got my boy, the breeder gave me a stern lecture that I should only use Interceptor, for the reasons you mentioned. At that time, judging by Sheltie List, almost all Sheltie breeders used Interceptor.

My vet eventually quit stocking Interceptor, but she special ordered it for me.

That was then - I don't know what the "current thinking" is on the matter.
 
I mentioned my concerns about Heartguard to my vet. She said that she was aware of the sensitivity and felt that heartguard was one of the safer ones for shelties and collies and also one of the more effective medications.
 
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