How Can I Treat My Cat's Heartworm Infection?

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heartworm treatment for cats

Heartworm in cats is pretty scary, so if your BFF winds up with a positive diagnosis, you’ll probably want to know what you can do about it.

It turns out that treating heartworm in cats is tricky because most cats never even show signs of the disease in the first place, and testing isn’t always accurate. Plus, the medicine that cures infected dogs of heartworm disease isn’t an option for cats.

So how can you help your heartworm-positive cat?

We spoke with Dr. Zach Marteney, a veterinarian and medical director at Meadowlands Veterinary Hospital in New Jersey, to find out what heartworm treatment for cats is actually like.

What is heartworm in cats?

Cats get heartworm disease when infected mosquitos bite them and pass along worms that live in their heart, specifically the pulmonary artery, which brings blood to the lungs.

Cats are actually more resistant to heartworm than dogs are. If an infected mosquito passes heartworm larvae to your cat, a lot of the time those larvae will die before they ever even get to the heart, preventing them from causing serious trouble.

But that doesn’t mean your cat’s completely immune. Even if just a couple worms make it to your cat’s heart, it could cause some major issues.

“Even with a much lower worm burden, heartworm disease is quite serious and can be life-threatening for cats,” Dr. Marteney told The Dodo.

Heartworm symptoms in cats

One big problem with heartworm disease in cats is that they rarely show any symptoms at all when they’re infected, making it almost impossible to diagnose.

In fact, the first sign of heartworm in cats is often sudden death because your cat won’t show any symptoms until the worms die and their bodies block crucial blood vessels in the lungs.

And if your cat does show symptoms, those signs are often misdiagnosed as asthma.

There’s heartworm testing for cats, but it’s not reliable as it only detects female heartworms — basically if your cat is only infected with male heartworms, it won’t show up in a routine scan.

Heartworm treatment for cats

Since cats rarely show symptoms, the most common heartworm treatment is actually no treatment at all.

“In cats with no clinical signs, allowing the disease to naturally progress is often the most reasonable course of treatment,” Dr. Marteney said.

Regular testing can help you determine whether or not your cat’s infection has passed, but because testing isn’t the most reliable, that only works if he was infected with female worms.

“Repeat testing every 6 to 12 months can help confirm that the worms have died — if there are female worms that can be picked up on the antigen test,” Dr. Marteney said.

Just keep in mind that there’s no way to know if your cat was infected with both male and female heartworms, so if the repeat testing shows the female worms have died, it can’t confirm that any males in his system also died.

If your cat actually does show symptoms of heartworm disease, surgery is possible — but it’s not always recommended.

“The worms can be surgically removed, but this is a complicated procedure that is only indicated in cats that are very ill from the disease,” Dr. Marteney said.

Heartworm medicine for cats

Unfortunately, there’s no medicine that can kill your cat’s heartworms.

“Treating heartworm disease in cats is more difficult than in dogs,” Dr. Marteney said. “We're not able to use the same type of adulticidal treatment to kill the adult worms. Melarsomine is much more toxic to cats than dogs.”

If you know your cat has an infection, you can ask your vet for steroids, which can help prevent complications that may arise when the heartworms die.

“Steroids can help with inflammation in the lungs and minimize the risk of an anaphylactic-type reaction to the worms as they die spontaneously,” Dr. Marteney said.

To keep your cat from ever having to deal with this horrible disease in the first place — and the risks that come with it — your cat should always be on a heartworm preventative.

Revolution Plus is a topical heartworm prevention medicine that also targets fleas, ticks and other parasites. It’s available for cats in the following weight ranges:

The bottom line is that treating heartworm in cats is tough, especially because you may never know that your cat even has the disease. That’s why staying on top of prevention is actually the best treatment possible.

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