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How Do Dogs Get Heartworms And What You Can Do About It

Sad dog with heartworms at the vetGo find yourself a measuring tape. Seriously, go get it. Now, measure out 13 inches. That’s how long a heartworm in your dog can be.

And, it is not uncommon for up to 30 of them to be huddled together in and around the heart of your infected dog.

Yes, heartworms are dangerous. Here’s what you need to know about them and tips on how to deal with this parasite that’s endemic to, pretty much, the entire USA.

What are the Signs of Heartworm Infection?

Here’s the problem: newly infected dogs typically do not exhibit any signs

It takes six months before the infection can even be detected using current methods. As the worm burden increases — this can take years — signs begin to appear.

For example:

  • Mild but persistent cough
  • Lethargy
  • Signs of fatigue with little exercise
  • A lack of appetite
  • Loss of weight.

As symptoms progress, the dog may experience difficulty breathing; ultimately, there could be a sudden collapse with death within a week.

But How Do Dogs Get Heartworms?

Dogs get infected through mosquitoes. But, it’s a bit of an extended process. First, the mosquito bites an already infected animal — this could be a wild animal.

Larvae from the infected animal enter the mosquito along with the blood meal. Heartworm larvae, for some reason, require living within a mosquito to reach the stage that make it dangerous to dogs … and it takes about two weeks for that to happen.

When that mosquito bites your dog, some of those infective larvae make it into his bloodstream. It takes a further six months for these larvae to grow into adult worms. Worms can live in a dog for 5 to 7 years.

Why Should I Take Preventative Action

If you don’t take preventative measures here is what’s in store of you:


Heartworms cause permanent damage to the heart and lungs

Because their presence reduces the efficiency of the right side of the heart, the heart attempts to compensate by growing in size. Trouble is that only makes matters worse.


Treatment to eliminate heartworm is High Risk for dogs

It requires strict cage rest for several months while the body deals with the dying worms — vigorous exercise can, literally, result in sudden death.


Recommended treatment for heartworm is frightfully expensive

Treatment can cost you hundreds of dollars. It’s not uncommon to spend over $1000.

On the other hand, the yearly cost of prevention is around $50, varying a little with the weight of the dog.

Currently, the American Heartworm Society recommends year-round preventative treatment.

What Can I Do to Prevent Heartworms

Clearly, preventing bites by mosquitoes will prevent infection. Equally clearly, that is pretty much impossible to accomplish.

Instead, there are simple monthly medications — chewables or topicals — that will kill larvae before they can become adult heartworms.

There is also a once-in-6-month injection that can be emplo