What Is Heartworm Disease In Cats?

It’s actually pretty scary 🙀

what is heartworm in cats

You’ve probably seen pamphlets and posters about heartworm disease at your vet’s office, but you might be wondering how exactly heartworms would affect your cat if he got them.

Heartworm disease is a parasitic infection that can affect your cat’s heart and lungs and have fatal results. But the signs are almost impossible to spot before it’s too late, which is why prevention is key.

The Dodo spoke with Dr. Zach Marteney, a veterinarian and medical director at Meadowlands Veterinary Hospital in New Jersey, to find out everything you need to know about heartworm in cats.

Heartworm disease in cats


Heartworm disease in cats can be pretty bad, since heartworms can make themselves at home in your pet’s heart.

“Heartworm is exactly what it sounds like — a worm that lives in the hearts of dogs and, in rare cases, cats,” Dr. Marteney told The Dodo.

These worms like to take up space in an important artery in your cat’s chest: the artery between his heart and his lungs.

“Technically it lives in the pulmonary artery (the large vessel that carries blood from the heart to the lungs), where they absorb oxygen and other nutrients from the blood,” Dr. Marteney said. “They spend their entire adult lives here, breeding and releasing microscopic worm larvae into the bloodstream.”

Heartworm disease is so serious for cats because these worms pick a pretty fatal spot to live. They could easily cause a life-threatening blockage, especially once they die and their bodies get pushed around by your pet’s blood flow.

How do cats get heartworm?


The only way cats can get heartworm is through mosquitos, which can feel daunting because they’re basically everywhere.

“A female mosquito bites an infected animal and takes a small blood meal, along with some microscopic worm larvae,” Dr. Marteney said. “The larvae grow and develop in the mosquito, and when they’re more mature, they are deposited on the skin when the mosquito bites another pet.”

Once your cat is bitten by an infected mosquito, any heartworm larvae on his skin will attempt to enter through the wound and make their way through your cat’s system and into his heart.

“They migrate through the mosquito’s bite into the subcutaneous tissues, then follow a complicated migration pattern through the pet’s body while continuing to mature,” Dr. Marteney said. “Eventually they arrive in the pulmonary artery, where they grow into adults and start sexually reproducing to continue the cycle.”

The good news is the larvae won’t always make it to your cat’s heart.

“Cats are more resistant to infection from heartworms than are dogs, so many times the larvae die before they are able to complete their migration to the heart,” Dr. Marteney said.

And if your cat does manage to get heartworm disease, he’ll usually be infected with just a small amount of worms compared to dogs. But keep in mind that even only a couple worms can cause serious, and even fatal, results.

“When a cat does become infected with adult heartworms, there is often a much lower worm burden,” Dr. Marteney said. “Most of the time, less than six adult worms are present (compared to many more in dogs), and there are often only one or two worms in an infected cat.”

Signs of heartworm in cats


One of the scariest parts of heartworms in cats is that they often don’t show any signs at all of an infection until the worms are dead.

But once the heartworms die, your cat’s bloodstream could push them so deep into his lungs that they block off oxygen from reaching crucial parts of his body.

These blockages can be fatal, which is why you might have no idea your cat’s even sick until it’s tragically too late.

“One of the most common clinical signs of heartworm disease in cats is acute sudden death, even in single-worm infections,” Dr. Marteney said.

If your cat does end up showing symptoms, they’ll only flare up when the worms first get to his arteries and won’t show up again until after the worms die.

And even then, these symptoms look a lot like asthma, so most cats with heartworm end up getting misdiagnosed and treated for a condition they don’t even have.

Do cats need heartworm prevention?


Cats absolutely need heartworm prevention, since the disease is so dangerous and almost impossible to spot. (And even if your cat does get diagnosed, most treatment really just consists of letting the infection run its course.)

There are two main types of prevention: topical ointments and oral medications. You’ll need to talk to your vet about which option is right for your cat, since these are prescription products.

Check out Heartgard chewable tablets from Chewy for $39.99

Or Revolution Plus topical solution from Chewy for $124

It’s so easy to keep your cat from getting heartworm, as long as you routinely give your cat preventatives.

If you do that, this disastrous ordeal is totally avoidable, which means it’s one less thing you’ll have to worry about. Instead, you can just focus on keeping your BFF happy and healthy.

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