Why Heartworm Prevention is So Important

I grew up in a climate that had long, cold, snow-covered winters.  While I am not suggesting that I found that situation enjoyable, it did tend to prevent situations like I faced this past January, where I spent several intense, moments trying to destroy the blood sucking pest that had somehow gotten into my home. During which, I probably looked like I was either having a standing seizure or engaged in a truly bizarre interpretive dance called, “who has mosquitoes in winter?!” And as many of you know, where there are mosquitoes, there is that scourge of the canine kingdom, the heartworm, eager to infect our susceptible canine fur-babies.
Here’s a basic breakdown of how heartworm disease works.
A mosquito carrying the parasite bites your dog, injecting him with any number of teeny, tiny larvae that are in what is called the Infective Stage.  At this point, the heartworm larvae are pretty much just hanging out in the dog’s tissue, waiting to grow big and strong and deadly.

If a heartworm preventative (for example, Trifexis or Interceptor) is given during the first 30 days of transmission, the larvae die off and life goes on as normal for everyone involved (except the heartworms, of course).  If a preventative isn’t given, however, the larvae develops to the stage where they can’t be killed off by a simple, easy-to-use pill, dig their way into your dog’s veins, and head to the heart and lungs, where they will start to do some serious damage.  The parasites that started off at a microscopic size can grow to be up to a foot long.
In addition to being seriously gross to look at, there is some speculation that the animal can feel the worms moving around inside of their hearts.  Never having had heartworms myself, I can’t say whether or not that’s the case, but just the thought that it’s a possibility makes me uncomfortable.
Once the worms have taken up residence in the heart and lungs, they start destroying tissue, and eventually, the animal will go into congestive heart failure.  That can start out with something as minor as a cough and lethargy and then progress to something like this:

Note the pot-bellied appearance of this animal. That is not pregnancy, that is fluid build-up.  As the heart becomes weaker from the worm-induced damage, it is not able to effectively propel blood throughout the entire body. As a result, blood pressure drops and fluid begins to leak out of the vasculature system and pool wherever gravity takes it.  In a four-legged animal like a dog, this tends to be the chest and abdomen.
If the heartworm infection is caught relatively early, the animal can usually be treated effectively before there is too much irreparable damage done, but the procedure can be long, and it’s going to cost significantly more than the preventative that would have stopped this problem before it got started. This is a serious disease that will kill a pet if left untreated. That’s why veterinarians are required to regularly test for heartworms before dispensing medication. The sooner you find the infection and treat, the less damage there will be to your pet’s cardiovascular system. The ideal scenario, though, is to kill the little monsters before they ever have the chance to harm your baby, by keeping them on a monthly preventative.
At CHAI, each dog is evaluated as an individual, and we use preventatives and treatments depending on the health of that animal. There are many different types of preventatives on the market, and helping our clients chose the best one for their dog is of utmost priority.