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Heartworm disease in Dogs & Cats: Signs and Prevention

Heartworm Symptoms in Dogs & Cats | BetterVet

Every year, thousands of dogs are diagnosed with a serious infection caused by the parasitic worm, Dirofilaria immitis. Commonly called ‘heartworms,’ these thread-like worms can grow up to a foot in length while living in your pet’s lungs, blood vessels, and heart. Unlike many other worms that primarily affect your pet’s gastrointestinal tract, these parasites can cause serious and potentially fatal lung disease, heart failure, and organ damage.

How Is Heartworm Disease Spread?

Your pet can contract heartworm disease through the bite of an infected mosquito. Because dozens of mosquito species can host and transmit these worms, heartworm disease can be found globally. Changes in weather trends, missed heartworm preventative doses, and relocation of pets all have contributed to the spread of heartworm disease in pets around the world.
It used to be the case that heartworm disease was found mainly in the south and southeast regions of the USA. While these warmer regions of the country still have a higher incidence of infection, no state is free of heartworm disease at this time and, often, a relatively heartworm-free region can have ‘hotspots’ of infection. Keeping your pet safe from heartworm disease is crucial no matter where you live. Once a mosquito transmits the parasite to your pet, it may take years to cause obvious clinical disease, but during this time, your pet’s health is being compromised.

Heartworm disease in Dogs

The severity of heartworm disease in dogs depends on how many worms are present, the activity level and health of the dog, and how long the dog has been infected. Early in the disease, your pup may exhibit no signs at all or may have just an occasional mild cough. In more severe cases of heartworm disease, fatigue, a persistent cough, trouble breathing and even fainting episodes can be common in dogs.
You may have heard plenty about heartworm disease and have diligently kept all your dogs on heartworm prevention their whole lives. But did you know that cats and ferrets are also susceptible to heartworm disease? While the dog is the definitive host for heartworms, many other species can be affected; the progression of heartworm disease is very different in each of these species, but can be quite serious in all.

Heartworm disease in Cats

Cats and ferrets respond to heartworm disease slightly differently than do most dogs. Because they’re generally smaller, it doesn’t take very many worms to make cats and ferrets quite sick. In cats, signs can range from very subtle to quite severe, including sudden collapse and death. The signs of heartworm disease in ferrets resemble those in dogs, but often show up much sooner because of the ferret’s smaller size. Paying attention to your furry family members’ energy, appetite, and breathing is a good idea; making sure they stay on year-round heartworm prevention is an even better one!

How Do I Prevent Heartworm Disease In My Pet?

Treatment for heartworm disease can be hard on your dog; the process can be long, expensive, and not without risk of complications for your pup. Additionally, there is no approved therapy for heartworm infection in cats and ferrets; treatment for these pets is primarily focused on stabilizing them through the course of their illness.
Luckily, heartworm disease is easily preventable in all three species! As early as 6-8 weeks of age, your pet can be started on a monthly prescription heartworm preventative like Heartgard or Revolution. Since mosquitoes can easily enter our homes, even primarily indoor pets should stay on year-round heartworm prevention. Your veterinarian can help you select a product that’s right for your cat or dog and talk to you about routine screening for heartworm disease. Regular testing and monthly doses of a preventative medication are the best way to keep your pet safe from this costly and dangerous disease.
For more information about how to keep your pets safe from heartworm disease, check out the American Heartworm Society’s informational website at and talk to your BetterVet veterinarian today!


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