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Heartworm Awareness and Prevention

Each year, heartworm affects millions of pets across the country, resulting in often debilitating illness and significant veterinary costs. To help raise awareness of heartworm disease and to promote early diagnosis and treatment, the American Heartworm Society has designated April as Heartworm Awareness Month. However, heartworm remains a year-round concern.

Heartworm is a parasite that lives in the heart, lungs, and associated blood vessels of its host, resulting in organ damage and in severe cases, death. Heartworms themselves range in size, with females sometimes reaching a foot in length

How is heartworm transmitted?

Heartworm is a vector-borne illness transmitted by mosquitoes. When a mosquito bites an infected animal, it takes in some of the tiny immature worms from the bloodstream. When the same insect bites another animal, the parasite is transferred to the new host.

What animals are affected by heartworm?

While most of us associate heartworm with dogs, the parasite can also affect cats, ferrets, foxes, and other mammals. Because the parasite dwells in the heart and major vessels, it can drastically impair cardiac function and result in dangerous vascular blockage.

What are the symptoms of heartworm?

Early in the disease process, a host animal may show few or no symptoms. However, as the disease progresses, your pet may exhibit:

  • Lethargy
  • Fatigue and reluctance to exercise
  • Loss of appetite
  • Persistent cough.

In advanced stages, you may notice:

  • Abdominal bloating
  • Pale gums
  • Labored breathing
  • Dark urine

If you observe any of these symptoms in your pet, seek veterinary care immediately. Failure to eradicate the parasite most often results in fatality.

Heartworm Prevention & Treatment

Heartworm disease is both serious and progressive, making early detection and prompt treatment essential to a good outcome. A simple blood test can identify the presence of heartworm proteins, but because animals with early-stage disease are often asymptomatic, many owners don’t realize when their pet could benefit from testing. 

Dogs. It’s recommended that dogs be tested annually for heartworm as part of their annual well-animal checkup. Puppies under 7 months of age can receive heartworm prevention measures.

Treatment for heartworm disease in dogs comes in the form of chews or pills prescribed by your vet. Preventatives can be purchased over the counter at your local pet supply store. 

Cats. Heartworms behave differently in cats than they do in dogs. Cats typically host fewer adult worms, and the medicine used to kill the parasite in dogs cannot be used in cats. Preventive treatment is the only option in felines.


Heartworm is a serious parasite-related illness can be fatal if left untreated. We join the American Heartworm, Society in encouraging regular heartworm testing for your pets. Because heartworm is a progressive disease, prompt diagnosis and treatment are essential to positive outcomes. Have your animals tested regularly and be vigilant for any changes in your pet’s behavior that could be indicative of heartworm disease.

Editor’s Note: Don't forget - with Figo's Wellness Powerup, you can get reimbursed for applicable preventative care that keeps your pet happy and healthy before any conditions snowball. Get a quote to learn more.

Cecily Kellogg is a pet lover who definitely has crazy cat lady leanings. Her pets are all shelter rescues, including the dog, who is scared of the cats. She spent eight years working as a Veterinary Technician before becoming a writer. Today she writes all over the web, including here at Figo.

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