Dog Heartworm Medicine

Just what is in dog heartworm medicine and when is it necessary? Let’s stroll through the lifecycle, med side effects and why natural herbs might be a better choice.

This is the saddest picture I ever took of Bonz but it's how we feel about dog heartworm medicine

The cause of Heartworm is the bite from a mosquito carrying the heartworm larvae but even that isn't a sure thing. Let's look at:

The Life Cycle of Heartworm

An infected mosquito bites a dog and delivers microscopic worms. These larvae have to find a way to the bloodstream and then to the heart.

Within six months, they can grow up to 12 inches and could either make your dog sick or finish it's lifecycle undetected. The worm completes its life cycle there and dies.

If heartworms produce offspring, they CANNOT grow and complete their life cycle inside your dog. First the tiny microfilaria must be sucked out of the dog by a mosquito. Once inside the mosquito, they must grow to a certain stage until they can be passed on to another victim.

Here are answers to a few heartworm questions you may have:

  • Is heartworm contagious?  No
  • Is heartworm medication necessary?  NO
  • What are heartworm symptoms in dogs?  Coughing and labored breathing top the list
  • Are there heartworm medication side effects?  Yes
  • Is there natural heartworm prevention? Yes
  • What is the best heartworm medicine for dogs? An herbal combination because they have no side effects and can both prevent and kill heartworm while preventing other internal worms and flea infestations as well - if done correctly.

The rest of this page should explain the reasons for the answers to these questions.

Dangers of Dog Heartworm Medicine

Before the vet prescribes heartworm medication for your dog he must test for heartworm.Then he must test each year thereafter.


It seems logical to test once. After all, there wouldn't be any point in giving the medicine if your dog already has heartworm. But why on earth would the vet need to retest each year if your dog is talking heartworm pills?

Here's the first thing I find scary:

  • Giving chemical heartworm preventatives to heartworm positive pets can cause a severe fatal allergic reaction.
  • Heartworm testing is not 100% accurate so testing each year gives a better chance of finding heartworms in dogs.

Note that there are two heartworm tests that can be done. The first shows whether the microscopic worms are in the blood, not whether they will gain access to the heart and grow there.

There is also a test which looks for waste from adult heartworms in the blood.

What is Dog Heartworm Medicine Anyway?

An insecticide. That's right. You pay to give your dog a poison pill once a month. Doesn't anyone else see a problem with this picture?

Is it because it's called medicine?  Seems to me there's millions of big dummies out there. But I suppose a lot less people would buy it for their canines if it was called what it is - worm poison.

I mean what would Heartgard's slogan be if it weren't a dog heartworm medicine? Obviously they chose the name Heartgard because it plays on our emotions. Would they say for Heartgard Worm Poison? Kill the worms and save your heart?

Hmm. That might work. Maybe I should change to advertising instead of the noble cause of saving dogs everywhere. (I know it's a lofty goal, but a girl has to try.)

Getting back the to point, dog heartworm medicine kills the worms at an early stage ONLY, thus the repeat monthly treatments. So "just to be safe", we're supposed to make our dogs take poison once a month for ten or fifteen years even if it's snowing?

 Side Effects of Heartworm Meds

Some years ago the vet told my ex-mother-in-law she must put her dog on heartgard. When I tried to talk to her about it she insisted it was completely safe because her vet said so, I shut up.

A year later she complained that every month when Duke got his heartworm meds he threw up blood and should she mention it to the vet. My eyes widened so big my eyeballs would have fallen out if not attached. "YES!" I told her.

What happened? He told her not to worry about it.

When I went to Heartgard's website to look for side effects I felt like someone was trying to pull the wool over my eyes. All it listed was Noticeable Side Effects which meant to me no one was going to talk about kidney or liver damage from long term use.

Vomiting blood wasn't mentioned. Instead I found this ...

"Noticeable side effects in dogs may include: dilated pupils, drunken gait, tremors, and loss of body weight"

In other words, signs of poisoning

The Nature of Pesticides and Immunity

On a lark while writing this page I browsed for just a couple minutes about Heartgard complaints. I've never given the product to my dogs so I've not kept up with any hubbub.

What I found was an article in Consumer Affairs by Truman Lewis about this popular dog heartworm medicine.

In 2002 the FDA told Heartgard to change the 100% affectiveness on their label because there were complaints of dogs getting heartworm on the product. They did not. In 2005 the company was reminded a bit more sternly. They agreed but still did not comply with the FDA.

The company claims they had evidence that heartworms had developed resistance to the active ingredients in Hartgard Plus,  the company was actively working to reformulate it. As of 2011 nothing had been done.

 I haven't searched for an update.

* * *

The point of reminding you about immunity isn't just that the dog heartworm medicine may not protect, but that insects, worms and bacteria all become immune to things that kill them and stronger toxins must be used.

It's a vicious cycle we don't have to be a part of if we use natural things that do the work of these man made toxic concoctions.

For both natural heartworm prevention and treatment without side effects, let me direct you to my page titled  Dog Dewormer. There you will find the basic remedy for all internal parasites. Just scroll on down to Worm Prevention and I'll explain, how, what, why and where.

A last note on commercial heartworm treatment for dogs. If you simply can't be bothered to learn the healthy alternative please use it only when necessary by doing the two following things.

First, there's an excellent map of the United States showing what months the pills are actually necessary for your dog depending on where you live. To check out the start and stop dates, visit this page at Tibetan Mastiff - heartworm.

second, know the actual length of protection is 45 days, not 30.  Why then are we told every 30 days? One vet told me its just easier for people to remember.

Another? Well do the math. Your dog would only need it 8 times a year instead of 12. Let's say it cost you $100 per year or $8.33 per month. Heartgard makes an extra $33 a year on you. And if they only sold to one million people a year it would be an extra $300 million each year by poisoning your dog needlessly.

Maybe it's time to just say no thank you.

Dog Heartworm Medicine to Health Problems

Important Notice

I sell NSP (Nature's Sunshine) herbs and supplements for your dog. While these are strictly tested and made for human consumption, I am the only one in the United States successfully using them for dogs for over a decade now.

To get proper doses for your dog you must purchase through me. I've spent a great deal of time learning the right combinations and doses per weight for your canine kid.