What You Should Know About Cats and Heartworms

Say heartworm and you probably think of dogs. But cats are susceptible to this infection, too. And once the parasites take up residence in kitty's heart, this difficult-to-detect infection may be life threatening.


The trouble is that many infected cats don't show symptoms. Other cats develop severe symptoms, but diagnosis can still be tricky. And although the heartworms often die off on their own (usually within 2 to 3 years), for many, especially older cats, the infection is fatal.

Heartworm Symptoms
For infected cats who do develop symptoms, here are a few that may appear:

Respiratory distress, such as coughing or labored breathing (often misdiagnosed as asthma)
Heart murmur
Lethargy


Lack of appetite and/or weight loss


Gastrointestinal upset (vomiting)


How It's Diagnosed
Studies have found that using all three of these not-always-reliable tests may increase the chances of an accurate diagnosis:
Chest x-ray
Antibody or antigen test
Echocardiogram
How It's Treated
Heartworms can't be cured, but symptoms can be managed. If your vet confirms a diagnosis, but your cat is not showing symptoms, ask whether it's best to wait for your cat to resolve the infection on his own (when the worms die off) or to try a treatment such as prednisone. Emergency measures such as oxygen support, intravenous corticosteroids, electrolyte therapy, and bronchodilators may be necessary in cats with severe symptoms.

Also, be aware that adulticide medications, such as melarsomine dihydrochloride, are often used to treat dogs but are very toxic and often fatal to cats and should not be prescribed.

How Cats Get Heartworms
Cats can't get heartworms from other cats. Rather, heartworm larvae are transmitted to cats via mosquito bites, so the risk is higher where mosquito populations are greater -- especially in hot, humid regions.

How to Help Prevent It
Whether you live in a humid or dry climate, ask your vet about the risks and benefits of a monthly heartworm-protection medication, such as ivermectin. Also, remove any containers of standing water from around your house; these are favorite breeding grounds for mosquitoes.