As a responsible pet parent, you know that you are supposed to keep your fur babies on heartworm preventive, but have you ever wondered why it is so important? What would happen if you didn’t? What if your pet has heartworms – what now?

We believe that information is power and there is A LOT of information on this dreaded disease. Over the next 3 posts, we will cover:

• An overview of the heartworm lifecycle and how prevention fits into disrupting it
• How the worms cause signs of illness and what the most accurate tests are for diagnosis
• What are the safest strategies for treatment

Overview of heartworm biology

So what are heartworms anyway? Heartworms are really just that, worms that live in heart of a dog or cat. But how do they get there?

By now you know that mosquitos are the way these little buggers get into our pets. Mosquitos can carry heartworm larvae (microscopic baby worms called microfilaria) which can enter into the bloodstream of a dog or cat when they are bitten by a mosquito. These larvae whoosh around in the bloodstream for about 6 months, getting bigger and bigger until they can’t fit in the small blood vessels anymore. This is when they essentially get stuck in the heart or, in the case of cats, in the large blood vessels in the lungs.

Once they are in the heart or lungs as adults, male and female worms start making babies (more microfilariae!) which also go out and whoosh around the entire blood stream. Adult heartworms can live for 5 to 7 years in dogs and up to 2 or 3 years in cats! This means that every mosquito season can potentially lead to higher and higher numbers of worms living in your pet.  As this cycle of reproduction goes on over months to years, the adult worms are continuously causing damage to the inside of the heart. In the case of cats, the problems are even more severe since the worms are actually in the lungs.

Pets with microfilariae circulating around in their bloodstream also pose a risk for other pets in the area as well by serving as a reservoir. Mosquitos can bite an infected dog, then carry the microfilariae to another dog and the cycle continues.

How does heartworm prevention work?

This is the part where you come in. The monthly medications that you give your dog or cat to prevent heartworm disease works by killing the baby larvae and microfilariae that may have gotten in via the dreaded mosquito bite. Every month you give the medication, you are potentially killing off a new round of invaders before they have the chance to grow into adult worms and cause disease.

This is why monthly heartworm preventive is critical in areas where there is any mosquito activity. According the recommendations from the American Heartworm Society, the safest option for prevention is for pets to be on heartworm prevention year round.

Our next post cover the basics of how the infection actually makes your dog or cat sick and what are the most accurate way of confirming a diagnosis. Stay tuned…