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Which heartworm preventative do you use?

Posted: Sun Jul 15, 2018 7:43 pm
by MaisyPancakes
Hey friends!!! I will post a real intro for my new dog (still no-name :eek2: :tired: ) and her spectacular MP-ODO story :love: , but have a quick practical question before I see my vet on Wednesday.

I'm going to start using HW stuff with this dog because even my vet mentioned last year that she pretty much insists on it at this point...unless the dog is very, very old or sick and barely go outside. Ten+ years ago (!) I used the Safeheart dose of Interceptor. I recall hearing about the "plain" Interceptor being discontinued or something but I just saw it being sold online, so I assume it's still available. ANYWAY! Is the Safeheart dose still the way to go? Is this dosing sufficient, even with the bugs and the strains being all crazy? What do you guys use these days?

Thanks so much! I feel like a newbie! :wink: :tongue:

Re: Which heartworm preventative do you use?

Posted: Mon Jul 16, 2018 4:11 am
by MaisyPancakes
ETA: I read some stuff on dogaware/Mary Strauss and an updated article for 2018 says due to the weird strains and all, she no longer recommends the lower Safeheart dose nor the 45-day schedule and thinks everyone should give it year-round.

New question(s): This dog got a dose of ivermectin while at the shelter. Does that mean I should stick with that (instead of milbemycin oxime) for the remaining season? Aside from milbemycin oxime's ability to Safeheart-dose and safety for MDR1, is there an obvious benefit to either type?

Thanks again! <3

Re: Which heartworm preventative do you use?

Posted: Mon Jul 16, 2018 5:52 am
by connie
Nana, if the dog has been started on ivermectin, that doesn't mean you have to continue that.

As you know :madgo: :cussing: I am a recent convert, and quite a fervent one, to giving preventive. Nothing like a case of heartworm to cause me to find religion!

My dogs are getting Sentinel (milbemycin oxime), and I will switch them to Interceptor as soon as I fill the scrips I have for that. My vet clinic only carries Sentinel and Heartgard.

I am not sure I'm comfortable with the 45-day interval, so it's interesting you bring up Mary Strauss's view. I may wind up going 30-day intervals for all my dogs, but I doubt I will give it in the dead of a Chicago winter.

I did a fair amount of reading about the MDR1 sensitivity -- did you know that 75% of Collies now carry that gene mutation?! -- and also talked to a friend who is a vet tech of 20 years, and I learned that, as this article says, "Given the mechanism for toxcity, there is no reason to consider milbemycin oxime safer for dogs with the mdr1-1Δ mutation than ivermectin." This is because "So-called "ivermectin" sensitivity is actually sensitivity to a broad class of compounds due to a basic defect in the blood-brain barrier. Normal dogs are protected from acute and often fatal neurotoxicoses when these compounds are administered as pharmaceuticals (including ivermectin) by P-glycoprotein, an ATP-dependent drug transporter that moves a broad spectrum of substrates across several tissue borders throughout the body. The normal gene encoding for P-glycoprotein is MDR1.

Basically, both preventives should be considered to have the same potential effects, one does not have a distinct advantage in that area, my reading told me.

However, that is not bad news necessarily, as the dose in heartworm preventive is now so much lower than it was 20 years ago -- when I absorbed my 'heartworm preventive is toxic!' message -- that a dog would have to consume an entire vet clinic of preventive tablets in order to poison itself. Given at the dose of monthly preventives, neither ivermectin nor milbemycin oxime has been shown to cause problems.

The same is not true of moxidectin, which is used in that injectable 6-month preventive, but you wouldn't give that anyway. :fie:

Once my dogs all gobbled down their preventive in May, when I started giving it this year (following Rowley's hw diagnosis in April) and nobody had any reaction at all, I relaxed and forgot about it. My vet tech friend assured me that sensitivity to the preventive would present itself immediately, in 99.9% of cases of reaction; she also told me the drug is out of their systems in 72 hours or less, so giving liver support for a few days is of course a good idea.

I love your new girl, Nana! How is she settling in with you, and you with her?

Re: Which heartworm preventative do you use?

Posted: Mon Jul 16, 2018 6:12 am
by connie
I looked at Mary Strauss's comments that Nana mentioned -- I found this:

"It’s best to give heartworm preventives year-round as well, not only for better protection against infection, but also to ensure that the manufacturer will pay for treatment should your dog become infected with heartworms."

I don't like that. My dog's health is one thing, the liability of a manufacturer is another.

Also, I found the American Heartworm Society website to be a really good source of information when I was doing all my reading this spring. ... guidelines

Re: Which heartworm preventative do you use?

Posted: Mon Jul 16, 2018 7:09 am
by MaisyPancakes
Thanks so much, Connie! <3 Interesting about MDR1 and how it doesn't matter which one you give. I might stick to ivermectin since she obviously did OK on it and it seems like if it weren't, it would be pretty obvious and immediately so.

When you get Interceptor, will you be using the Safeheart dose, or the regular dose? IIRC, the larger/regular dose is supposed to be for killing the "other worms," but I guess I never figured out if this is because the other worms are more badass than HW and you need more drugs to kill those, or for some other reason. In any case, like you, I'm far less afraid of these kinds of drugs than I am of HW at this point!!

Yep, saw Strauss's rationale behind the year-round schedule being more about manufacturer liability :/ ; there was something elsewhere ( and some PDF from an old talk from the early 2000s, I think) about how a 12-month schedule also brings down the possibility of infection down to 0% (versus ±4%). Anyway! I'll read up on the heartwormsociety page—thank you! :D

No-name-puppy is doing great, and we get along really well, thanks!! <3 She is less nuts about food (think about it/taste it first, as opposed to MP who was "in the mouth NOW and probably won't think about it later either!" so I'm still exploring how I can *really* reward her when she does good stuff. She isn't offering a ton of behaviors to mark (like tricks type stuff), but my trainer reminded me that I've known her for a grand total of 7 days, so don't even expect anything like that for a month or two. HA! ;) I've been meaning to update about her on FB and here—I'm totally out of practice for managing time and am trying to get used to it! :S

Re: Which heartworm preventative do you use?

Posted: Mon Jul 16, 2018 7:59 am
by connie
I thought that was interesting, too, that the MDR1 mutation is not about a sensitivity to ivermectin per se, but is an indicator of a deficiency in the blood-brain barrier. I also read that the 'don't give ivermectin to herding breeds!' warning was due to the practice of using HIGH doses of ivermectin to treat heartworm in some protocols, with pretty awful effects for MDR1 dogs -- but a HIGH dose of milbemycin oxime would have produced the same awful effect. So the 'ivermectin is dangerous for Shelties and Collies' thing turned into a sound bite but the facts are a bit more complex.

I am giving, and will continue to give, the prescribed dose of preventive for the dogs' weight. This is one way, I think, that Rowley's heartworm treatment has radicalized me: being compelled to have my dog receive three injections of an arsenic-based carcinogenic compound has made me less reactive about things like the dose of milbemycin oxime in a monthly preventive. Rowley has a medical exemption to rabies vax for the rest of his life, but I'm not sanguine about those Immiticide injections and their effects on his long-term health. In comparison, if I give HepaClenz for three days when I give Beau a dose of Interceptor for his weight range, I'm really not bothered by that. I guess my perspective has shifted. :tongue:

I'm not ready to give the preventive year-round, but with climate change fucking up the entire globe at such a rapid rate, I am not ruling that out in future, either!

Yes to the settling-in period for all dogs in new environments! In rescue we go on the assumption that it takes about two weeks for a dog to show its true personality when it's been put into a new home, be it adoptive or foster. I had one rescue Sheltie, way back when, who showed this dramatically: Lexi was a princess, a model Sheltie girl, for about 12 days and then, when I got up to go answer the door one afternoon, I came back to find her *standing on the coffee table* eating my pizza. Clearly she had settled in at that point. :lol: So I hope you and TBD settle in with each other and come to discover all kinds of nice things about one another. I did love MP's willingness to consume every food on offer, but that's kind of unusual, so you might not have come across that again in TBD.

Re: Which heartworm preventative do you use?

Posted: Mon Jul 16, 2018 11:52 pm
by maxs_mommy
I use interceptor, full dose for weight but on the 45 day schedule and seasonally but the off-season has been getting shorter every year it seems. Interceptor did go off the market but it was bought by another pharma and is back in production. I know, if your vet will write the scrip, Drs foster and Smith has it.

Re: Which heartworm preventative do you use?

Posted: Thu Jul 19, 2018 5:32 pm
by MaisyPancakes
Thanks so much, friends!! I talked to my vet yesterday and she said she typically uses Heartguard these days (partly because Interceptor became unavailable like Ashley said, and they were like FU then; also because she thinks the dose of ivermectin is minimal/low in a good way). I told her that I'll ask for a script when it's time, so I'll ask about 30 versus 45 days and decide which kind by then. :)

Re: Which heartworm preventative do you use?

Posted: Sun Aug 19, 2018 11:23 am
by yintzy
MP, Yes, I did all that research when Interceptor was unavailable. I think they did worry about dogs on the cusp of the weight ranges on the box - so dogs on the low end, getting too much ivermectin - think a 26lb dog getting the dose enough for a 48lb dog. I went with Iverheart Max because the weight ranges worked for my gang but then it was recalled due to not enough ivermectin. Thankfully, no one had a positive result. I use Sentinel now - and I use frontline too!!!!