Heartworms, also known as Dirofilaria immitis, are a type of roundworm that when mature will reside in the hearts and lungs of infected animals.

Who gets heartworms?

According to the American Heartworm Society, “Heartworm infection primarily infects dogs, but infection may also occur in cats. While cats may not be infected as frequently as dogs, diagnosis in cats is on the rise.

Ferrets as well as other mammals such as wolves, coyotes, foxes and even sea lions can be infected with heartworms. Outdoor pets are at greatest risk for infection, especially in regions of the world where mosquito populations are high. However, even indoor pets become infected by heartworms as infected mosquitoes can get into houses.”

How can my pet get heartworms?

Heartworms are transmitted by mosquitoes. A mosquito bites a heartworm infected animal looking for a blood meal and in the process picks up immature heartworms, called microfilaria, found circulating in the blood.

While the microfilaria are inside the body of the mosquito they mature into a stage that is infective and are then transmitted to an uninfected animal when the mosquito attempts to bite them.

The larva then matures further in the animal’s body and when fully mature, makes their way to the heart and lungs where the problems are caused.

What are the signs of heartworm disease?

Because heartworm disease affects the heart and lungs, signs associated with heartworm disease usually point to heart and lung trouble. Signs may include: coughing, decreased exercise tolerance, lethargy, and poor appetite which can also result in weight loss.

Can my pet be tested for heartworms?

Yes. Heartworm disease can be detected in a simple blood test. Tests will only show accurate results 6 months past the last exposure to mosquitoes as it takes that amount of time for heartworm larva to mature inside the pet’s body to a stage where they are detectable by testing.

Heartworm tests can be performed in your veterinary hospital with a brief appointment. Some hospitals have the ability to do “in hospital” testing with results in under 10 minutes while others may send their samples off to an outside lab where the results may be available within a few days.

Can I prevent heartworm disease?

Heartworm disease can be prevented with the use of preventive medications that come in a variety of forms. Heartworm preventives act by killing off microfilaria, preventing them from maturing into adult heartworms. These medications come in once a month chewable tablets, treats and topical products that are applied to the skin.

Heartworm preventives are also available in the form of a season long injection. The key to heartworm prevention is owner compliance with giving the medication on time for the entire season. Even missing one dose can increase your pet’s chances of encountering heartworm disease.

What if my pet gets heartworms?

If your dog has heartworm disease, medications can be given to kill off the adult worms in the body. This can be risky as some dogs can have up to 250 worms present at one time which can cause congestion of the heart and lungs, preventing proper blood flow.

Treatment may require a stay in the veterinary hospital where your pet can be closely monitored and treated should complications arise.

Currently, there are no medications available to rid a cat of adult heartworms. In some cases, cats with heartworm disease will spontaneously resolve on their own for unknown reasons. Cats tend to only have 1-2 worms in their body at a time, which lessens the chance of heart and lung congestion when the worms die off.