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Heartworms: The Preventable Deadly Disease

Before we dive into heartworm disease, its devastation, its transmission, and its prevention, I would like for you to ponder a few questions. How many times have you stood in front of your mirror on a hot summer night and noticed a mosquito or two (or three) swarming around your bathroom light? Even though you are inside in the air conditioning, those mosquitos snuck in with you as you walked into the house after an evening of gardening. But, your dog never goes outside, right? That's what you tell the veterinarian when he asks if your dog is currently taking heartworm prevention. Your dog is trained to potty on a pee pad and never goes outside. Sound familiar? Well, (despite the fact that I would encourage you to let your dog outside at least once a day for enrichment if they "never go outside"), you now recognize the fact that mosquitos will follow you into the house, right?

Okay. Now that you recognize that, I will remind you that mosquitos carry heartworm (Dirofilaria imitis) larvae. Heartworms are transmitted by mosquitos. Heartworms are NOT transmitted from dog to dog. Heartworm disease is also not detected on a fecal examination as some may believe. Heartworms are a parasite that invade the heart, blood vessels, and other major organs. Heartworms are not an intestinal parasite. Heartworms ARE deadly.

Alright, so let's go over the heartworm life cycle, transmission, etc., real quick. In a nutshell, a mosquito bites a dog. When taking a blood meal, the mosquito injects a heartworm larvae into the blood vessels of the skin. Once in a blood vessel, the larvae finds its way to the right ventricle of the heart. There, it sets up a home, grows to an adult, and waits for another mosquito to inject another worm into the blood stream. Once there is at least one male and one female worm in the right ventricle of the heart, they begin to reproduce. They send their offspring back into the blood stream to circulate around, with the potential to cause blood clots to the kidneys, liver, and even the intestines. Not to mention, some of the offspring also become adults in

the right ventricle and continue to multiply and have offspring. A dog can have several adult heartworms living in the right ventricle before showing signs of heart failure, or could have as little as two adult worms in their right ventricle and show signs of heart failure.

My point: heartworms cause heart failure. Even if your dog never goes outside, they can still succumb to heartworms and heart failure. Even if your dog never goes outside, they can still succumb to heart worms and heart failure from those pesky mosquitoes that make their way into your home.

How do a few (or a lot) of worms in the heart cause heart failure? My mind likes to keep things simple, so here is my explanation of how heartworms cause heart failure.

Let's say you have a swimming pool pump that is brand new. It provides beautiful clean water to your pool, and removes dirty water and sends it to a filter for cleaning. Over time, that pump can obtain build up from minerals in the water, dirt, leaves, hair, etc. Once the pump has too much build up, it will have a difficult time pumping through all the clog from debris, build up, etc. The pump tries as hard as it can but cannot push water/liquid through. It then shuts down because it overworks itself and can no longer function.

This is what happens when heartworms invade the pump in your dog's chest (the heart). It eventually to tired and weak because it physically cannot pump enough blood through the heartworms to keep up.

The good news is: we can prevent 100% of heartworm infestations with affordable prevention. Several options exist, and each veterinarian has their preference. Ask your veterinarian what’s right for you and your dog.

If your dog does become infected with heart worms, treatment is available and is not AS hard on your dog as it once was. Ask your veterinarian if your dog is a candidate for treatment. But remember, even after treatment you must keep your dog on heart worm prevention in the future.

For more information and detailed illustrations, please visit:

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