Tuesday, August 31, 2010

Your Vet Has a Heartworm Medication Secret

In yesterday's post, I mentioned that folks are giving monthly doses of insecticide to their dogs to prevent heartworm, but that an every-other month dose in warm weather will do just as well, and that your dog does not need to be dosed at all during cool weather (night time temperatures of under 57 degrees).

I have, of course, written about all this before and I encourage folks to go read that now.

None of this is new, of course. In fact, it was spelled out in a 1998 article by David H. Knight, DVM and James B. Lok, PhD. published in Clinical Techniques in Small Animal Practice and entitled Seasonality of Heartworm Infection and Implications for Chemoprophylaxis. As Knight and Lok note in that paper:

The practice of some veterinanans to continuously prescribe monthly chemoprophylaxis exaggerates the actual risk of heartworm transmission in most parts of the country and unnecessarily increases the cost of protection to their clients.

The authors go on to say, in a nice under-stated way, that heartworm hysteria pays a nice dividend for vets.

There is also a tremendous financial incentive to veterinarians to promote heartworm chemoprophylaxis because they control distribution of these excellent products in a market that is already large but not yet saturated. Unfortunately, preoccupation with worse case scenarios imparted by the profession to our client's and what could be perceived as an obvious economic self interest for veterinarians to promote chemoprophylaxis has encouraged an insidious overuse of a good thing. The well-intentioned promotion of heartworm awareness and prevention may overshadow the fact that in the temperate latitudes, heartworm transmission is seasonal and chemoprophylaxis is not necessary on a continual basis.

Knight and Lok note that vets hide the truth from their clients because it is in their financial interests to do so.

[W]hat harm is there in liberally dispensing these drugs? The issue that needs to be considered is whether medical justification should prevail over entrepreneurial interests in dispensing drugs intended to prevent rather than cure disease? Because veterinarians are permitted to sell the drugs they prescribe, use may not always be based strictly on medical justification...

... [G]iven what is presently known, continued adherence to a policy of superfluous chemoprophylaxis is disquieting because financial expediency for the veterinarian conflicts with clinical objectvity, and client consent is predicated on unrealistic expectations. Clients mistakenly believe they are purchasing additional protection for their pets, but in reality they are not. If the truth were known to them, few clients would agree to unnecessarily double their expense for heartworm prevention.


But is this the kind of information your vet will tell you?

It is not! And why not? Simple: there's no money in the truth.

And so the vets beat the drum of dependency and over-medication, abetted by the "American Heartworm Society" which is entirely funded by companies that sell heartworm drugs and testing kits. It's a bit like Penzoil writing your car manual and advising you to change your oil every month. Your car mechanic would then point to this manual to justify his services and sales -- and yes he only uses Penzoil in a car like yours! Perfect!


Viatecio said...

If one chooses to follow this protocol rather than that prescribed by vets, how does one ethically lie to say that "Yes, my dog is on HW prevention every month" just to avoid having to pay another fee for the HW test in order to buy more HW prevention?

It's easy to see how it can just be done (same as someone can just buy vaccines from a place like Fosters & Smith and just stick the labels on their dog's health record without actually giving the shot, so it appears that the dog is "up-to-date"), but it would just leave a bad taste in my mouth to have to do that.

I got over the criticism for using pinch collars and e-collars pretty quickly, since "anyone" can be a dog trainer, but I just have a different feeling when trying to pass over the heads of someone with letters after their name, especially in the medical field...even if I'm in the right (if not "right").

I'd love to be able to vet my dog according to it's needs rather than to a protocol, but the entire pet industry makes that very hard to do without sounding uncompliant or ignorant. Any way to get around it other than just sucking it up and telling a little white lie here and there? Seems that reputations take a hit when that goes on for a while...

Pai said...

Speaking of 'preoccupation with worst case scenarios', have you noticed how lately they've started trying to push monthly HW dosing and yearly testing of cats, too? That has even -less- scientific basis than doing it for dogs!

Seahorse said...


I'm coming to terms with all of this with my new pooch, and have had some moments of concern. Old habits die hard, even when I want to do the very best for my animals. "New" ideas, however I've fully embraced them, have sometimes confused me, even as I read myself blind and look inward to my own experience. It's emotion and habit vs. "the new", and the old has a fear grip on our hearts.

I think it will take confidence and practice in saying "No thank you" when confronted by our pets' health care providers. And in order to affect change we'll have to say "No" out loud, rather than fib our way out of uncomfortable situations. I've already done that several times, felt good about it, and later become concerned I'd screwed the plan up in various ways. It will get better with time, and by the grace and kind reassurances of those who have been saying "No" longer than I have. You know who you are. ;)


PBurns said...

Viatecio, read the origial post at the link.... the one where I say "go read that now" and is underlined and linked ;)

If you dog has been on heartworm medicine for the last year, why would a vet have to test the dog in order sell you more heartworm preventative? Think that through!

Hint: the answer is to increase his or her billing, not because it is medically necessary.

Second, why are you going to a vet for heartworm medicine?

I can assure you that folks with score of dogs -- kennels full of dogs -- are NOT going through that nonsense. They are using farm ivermectin (made by the same company as makes Heartgard) and dosing their dogs just as I suggest in my instructions at the link. And they have been doing this for more than 25 years.

In fact, one of the regular readers of this blog, who has something like a dozen border collies, does exactly this. He writes: "BTW we don't use prescription heartworm preventative. Quick math revealed prescription meds would run about $4/dog/month while livestock meds would run $0.04/dog/month for exactly the same drug. Our vet is aware of our practice and has no issues with it."

Of course he doesn't. His vet knows he's dealing with a dog man who has farm stock. Hard to snooker a dog man with farm stock on THIS topic! And if you use farm ivermectin or order it pre-mixed from the fellow I mention (which is what I do), you can dose your dogs every month if you want to as is really does become that cheap.


Staff of the Mendocino County Library said...

Even my most conservative veterinarian says to only give heartworm tablets between May & October and it should probably be between June & November since Heartgard and its ilk is NOT a preventative, it is an immiticide, it kills the microfilaria. I only give it every 6 weeks and there are a fair number of mosquitos. On most breeds you could mix up some ivermectin easily enough. Like all issues, there are good doctors and good veterinarians and then there are those inbetween and the ignorant and truly bad.

Having seen, in the rather poor rural county where I live, some truly bad cases of dogs with heartworm, I think addressing it as is important as making sure that we reduce the poisons that we expose ourselves and ours dogs to.


Marge said...

A sizable minority of herding breeds carry one or two copies of a gene mutation which results in a neurotoxic buildup in the brain. Giving these dogs Ivermctin (Heartguard) can be fatal.

There's more info about this at
busteralert.org .

I live in a high-incident heartworm area, so I give my collie Interceptor (Milbemycin oxime) during the hot and warm months, none during winter.

PBurns said...

Thanks Marge, but again, see the original link on heartworms where this is gone over in detail.

Mark B (who has a dozen working border collies) writes me in response to your note to say:

_ _ _ _ _ _

"The drug companies long before the research into the source of this issue knew that some collies were sensitive to ivermetcin and tested the effective minimum dose on these dogs. They found that there was no adverse affects up to 10x the effective minimum dose. This was later retested in academia and confirmed.

"Beyond that, the dogs that have this mutation are sensitive to ALL heartworm preventive since all these drugs are from the same class of drugs. Again, the doses used to prevent HW do not yield adverse reactions in dogs that have this genetic mutation."

_ _ _ _ _ _

Mark is correct, of course.

That said, in an abundance of caution I note the *potential* problem in my original heartworm post at >> http://terriermandotcom.blogspot.com/2008/05/billion-dollar-heartworm-scam.html


Moochies Mother said...

In years past on the ranch we used to worm the dogs with the horses. When we pasted with Ivermectin, what was left on the tube was wiped out with a finger and divided up with the dogs. Not very scientific but got a ballpark dosage and it worked while not wasting high dollar paste when you were running 25-30 horses and dogs. But now that I only have my little JRT and I take to the vet occasionally, they require that I HWtest every two years. I have only had him 6 months and I give him Heartguard every other month in the summer. In two years if she gives me any shit over testing, she's fired.