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What are Heartworms?

The important facts:

Heartworms can’t be spread from pet to pet.

They are spread through the bite of a mosquito.

Heartworms can be deadly.

It can be treated, but it is costly.

The best course of action is prevention.


Let’s get into it

Once bitten by a mosquito and not on monthly preventives, heartworms are found in the animal’s heart, lungs, and associated blood vessels. If left untreated, they can cause severe lung disease, heart failure, organ damage, and even death.

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The timeline of heartworms

Once bitten, it can take heartworms 6 to 7 months to mature from larvae to heartworms. Once inside an animal, the heartworm’s lifespan can be from 5 to 7 years.



At first, many see no symptoms or occasional cough. As the heartworms are left untreated, owners can see tiredness, consistent coughing, and an unhealthy appearance. If they are still untreated, you can see caval syndrome which is when there is an overflow of worms that block the flow to the heart. Caval syndrome’s only solution is surgery- which has a high risk of death even after surgery.

The main takeaway is that heartworms can kill if left untreated by damaging the heart, lungs, liver, and kidneys.



Heartworms can be treated with Melarsomine dihydrochloride which is a drug approved to kill heartworms and is given by injections. This treatment is costly and can potentially cause complications in dogs.

Don’t want to break the bank? Monthly preventives can prevent heartworms and the complications that can be caused by them. Monthly preventives are a cost, but cheaper than treatment and your pet won’t have to go through the pain caused by heartworms.


Heartworm cases are increasing each year. Are you giving monthly preventatives to keep your pet safe?

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Find more information here.  

Make sure to also check out the BISSELL Pet Foundation for more information here.