“My cat never goes outside. Why do I need to worry about heartworm disease?” You may have asked yourself this question when you saw an ad for preventing feline heartworms. But just like the stink bugs many of us in Maryland find flying around our houses all winter, mosquitoes can get into your house and infect your cat. It only takes one! Why would you not want to prevent this easily-preventable but frequently fatal disease in your indoor cat? And if your cat does go outside, it’s imperative that you prevent this dangerous disease.

You may not have heard much about this disease in cats, but heartworm disease is not just a dog problem anymore. Over the last several years, the veterinary community has recognized this as a serious problem in cats. Heartworm disease in cats is very different from the canine disease and it is equally serious. In cats, the name “heartworm disease” is a misnomer as it mostly affects the lungs, unlike dogs. The geographic risk for heartworm disease is the same as that of canine infections. Maryland is a known area for contracting this disease.

At A Cat Clinic, we have had seemingly healthy adult cats die suddenly from heartworm disease. We confirmed the diagnosis via necropsy. There was a third case where the worms were seen during an echocardiogram (ultrasound of the heart).

How does my cat get heartworms?

Heartworm infection takes place when a mosquito carrying microscopic heartworm larvae bites a cat. The larvae enter the tissues and migrate until they reach a blood vessel. They enter the vessel and are carried to the heart and lungs. They prefer the arteries in the lung where they will settle and cause inflammation. Eventually, the worm will die causing a severe inflammatory reaction that may be fatal to the cat.

What are the clinical signs?

Sadly, sudden death is the most common symptom we see in cats. Other symptoms include coughing, difficulty breathing, vomiting, lethargy, decreased appetite, weight loss, rapid heart rate, fainting, and collapse.

How do you test for heartworm disease?

Diagnosis is difficult in cats. There are two blood tests, an antigen test and an antibody test, but these are fraught with problems in interpretation. Other tests can include chest radiographs and an ultrasound of the heart. Unfortunately, the most common way we find heartworms is at necropsy.

How do you treat heartworm disease?

There is no approved treatment in cats!! We can only manage the inflammatory response caused by the worms in the lungs.

Since there is no treatment, prevention is the best protection! Just 1 or 2 worms are enough to cause potentially fatal disease. There is no such thing as an outdoor only mosquito; indoor cats are at risk for this disease. It only takes one mosquito to infect a cat. One study showed that >25% of cats diagnosed with adult heartworm infection were considered “indoor cats” by their owners. The Companion Animal Parasite Council and American Heartworm Society recommend monthly heartworm protection for cats in endemic areas (like Maryland).

All heartworm preventatives are easy to administer and very safe. You can only purchase heartworm preventative products from a veterinarian. Please stop by so we can discuss heartworm prevention for your cat. At A Cat Clinic we carry Revolution® (Selemectin, topically), and Heartgard® for Cats (Ivermectin, orally). I prefer Revolution ®, it is a broad-spectrum parasite prevention product. Revolution® treats, controls, and/or prevents fleas, gastrointestinal parasites, ear mites, and heartworms.

For more information please visit The American Heartworm Society website at this link and watch their video. http://www.heartwormsociety.org/pet-owner-resources/feline-heartworm.html#top