Pet advice: Cats can get heartworms, too

Q: Our cat Bart was diagnosed with heartworm disease. We’ve always had dogs so we know all about preventing heartworms with a monthly pill, but we didn’t even know cats could get this. Our vet said it was really common and that nothing could be done for it. If that’s true, why don’t veterinarians recommend monthly medications for cats too?

A: Your question raises several concerns: 1) What’s heartworm disease and does your cat truly have it? 2) How prevalent is heartworm disease in cats? And 3) what should veterinarians be doing to help address the possibility of heartworm disease in cats? Here’s my take:

Though cats are far less likely than dogs to get this parasitic disease, it is possible. Here’s how: As you may know from your experience with dogs, mosquitoes can carry heartworm larvae. If a cat is bitten by an infected mosquito, its immune system is typically capable of thwarting the parasite, thereby avoiding infection. Some cats, especially those who are bombarded by infected mosquitoes and/or immunosuppressed, may not be so lucky.

Some cats with heartworm disease never show any signs. And when they do, they can be confused with the signs of many other diseases, including feline asthma. Affected cats may vomit, cough and have difficulty breathing.

Unfortunately, symptoms alone won’t be enough to diagnose the disease. And laboratory tests can be confusing. In fact, the most common blood test for cats (referred to as an antibody test) will only prove that a cat has been exposed to the parasite.

In other words, the vast majority of cats who come up positive will not have an active infection. Additional blood testing along with X-rays and ultrasound may be in order before diagnosis can be confirmed. So be sure you follow up with your veterinarian.

So how prevalent is feline heartworm? The American Heartworm Society estimates that a million dogs in the U.S. have the disease. And while not all veterinarians routinely test cats, the findings of those who do suggests that about 20 percent of cats in South Florida have been exposed.

In case you’re wondering, even indoor living doesn’t prevent this problem. Multiple studies have proven that more than 25 percent of heartworm-infected cats live indoors exclusively. So just as for dogs, your best bet is to use monthly heartworm prevention products. Revolution and Heartgard are common brands. Ask your veterinarian.

Dr. Patty Khuly has a veterinary practice at Sunset Animal Clinic in South Miami. Her website is Send questions to