Canine Heartworm Disease

I’ve seen the first mosquito! That’s means it’s time for dogs (and cats, and horses, and people!) to catch heartworm disease. No fear though, it’s my favorite diseases: one that I never should have to treat. Just 1 tablet per month, at a cost of $5-10 per month and you don’t have to worry about it. Ok, I put the cart before the horse. First, go here:

http://www.heartwormsociety.org/article.asp?id=17

These guys will tell you everything you need to know about heartworm disease.

Now, go to your regular veterinarian and get the heartworm test, to make sure your dog is not already infected. Once you get your dog’s negative result you can start giving the pill once per month. That’s all you need to do!

What do you do if your dog is positive? That’s more complicated. I can tell you that dogs which are not yet showing signs have a very good prognosis, if you do it right. Let’s get on to the first myth, shall we?

Myth #1: I don’t need to get the expensive heartworm treatment, I can just put my dog on the prevention for 6 months and he’ll be heartworm free.

This myth has killed more dogs than I can count. The monthly prevention, when given for 6 months or more, will render the female worms sterile while shrinking both sexes, but not kill them. The worms can live for up to 2 years in this state. Since most of the current tests react to the proteins produced by fertile females, the test can be negative long before the worms are dead. To sum up: You give heart worm prevention for 6 months, you get a negative test, your dog still had heartworms for up to 1.5 years.

Myth#2: I don’t need to give heartworm prevention; I use a product that repels fleas, ticks and mosquitoes.

This has yet to be proven. And since 1 mosquito can transmit up to 10 heartworm larvae, I think you should err on the side of caution. How well does your citronella candle work?

Myth#3: My dog’s heart is fine, he can’t be that sick.

Heartworms are so named because that’s where they live. They actually cause most of their damage in the lungs. The heart “damage” is actually caused by high blood pressure in the lungs, which explains why much of the “damage” goes away when you kill off the worms.

Myth#4: Heartworm treatment is dangerous.

This is only partially true. Most of the time I hear this just because people don’t want to spend the money. Most of the dogs I treat do just fine. In fact, out of over 100 dogs I treated post-Katrina the only one that died came to me so sick we actually discussed euthanasia instead of even trying to treat her. She died within hours of the injection.


Heartworms are completely preventable, and the stuff is cheap. There is no reason for me to ever lose a dog to this disease.