Q&A: Does my dog really need heartworm prevention in Colorado?

I get asked this question a lot.


Many folks in Colorado have been under the impression that heartworm disease isn’t anything to be worried about in our state, so their dogs don’t need to take monthly heartworm preventative medication.  While that may have been true many years ago, today the reality is very different.

Take a look at this map from 2013 – it should be apparent that heartworm disease is a problem in Colorado, whether you live in Broomfield, Denver, or the mountain towns.


Heartworm Incidence 2013



The theory behind this increase in heartworm disease is that heartworms traveled here from other states via infected dogs.  Remember Hurricane Katrina?  Remember all the homeless dogs who found new homes around the country?  Those dogs, lovingly adopted by local Coloradoans, brought heartworms with them.  And since our native dogs in Colorado have not historically been treated with heartworm preventative medication, they were at risk.  That’s just one example.

How does a dog get heartworms, you ask?

Well, simply put, heartworms are transferred from dog to dog via mosquitoes.  With Colorado’s unpredictable weather, mosquitoes can pop up pretty much any time of year.  That is why veterinarians recommend year-round heartworm prevention.

In fact, studies have found that most positive cases of heartworm disease in Colorado occur during February and August.  Dogs typically will not test positive for heartworms until six months after they are infected, so that means those positive dogs were infected in the winter AND the summer.

There are plenty of reasons to keep your Colorado dog on heartworm prevention.

If you’re still not convinced that your Broomfield/Westminster/Boulder pup should be on heartworm preventative meds, consider this:  If your dog contracts this disease, he will have to be treated with arsenic-type drugs to kill the worms before they do serious damage to your pet’s heart and lungs.  This treatment costs up to 15x more than a 12-month supply of heartworm prevention.

Keeping your pet on heartworm prevention is easy and inexpensive.  Testing your dog for heartworms is also easy and inexpensive, and should be done every 12 months, whether or not your dog is on preventative medication.

Here’s the bottom line:  the more folks in Colorado who protect their pets from heartworm disease by giving preventative meds, the less dogs will be infected and allowed to spread this nasty disease.  It’s a win-win!


Want more info?  Check out The American Heartworm Society’s webpage!

Does your dog need to get started on heartworm prevention?  Give Dr. D a call to set up an appointment!


This post was updated to show new data from 2013.