Move Over Dogs. Heartworm Disease In Cats Is On The Rise

It's nearly spring. Time to trade in the snow shovels for lawn rakes, break out the shorts and flip flops, and stock up on mosquito repellent. The upcoming onslaught of mosquitos means it's also time for your annual visit to the veterinarian for your dog's heartworm test and preventative medicine. But it might be a good idea to include your cat on that mission. Although much less common, your cat can be affected, even fatally, by heartworm disease, so it's a good idea to learn all you can about this parasite.

What Is Heartworm?

Heartworm is an internal parasite that is spread by mosquitos and is therefore more prevalent in areas with a high mosquito population. However, because of our increasingly transient population, it is becoming much more common in all areas of the country. The parasites migrate through an animal host's body and settle in the lungs or heart, where it can cause circulatory, pulmonary, and cardiac illness, even death.

How Is Heartworm Transmitted?

When a mosquito infected with dirofilaria immitis (the heartworm parasite) bites a host animal such as a dog or cat, it injects the immature parasites called microfilaria into the animal's skin. These microfilaria migrate through the skin toward the heart and lungs. Along the way, they go through several larval stages, eventually maturing into adults and taking up residence in the lungs, heart, and circulatory system. These adults reproduce, and the offspring are spread when a mosquito bites the animal and becomes infected, starting the lifecycle anew. The adult worms are big enough to cause severe heart and lung disease and circulatory blockages.

What's Different About Feline Heartworm?

Cats are not a natural host for dirofilaria immitis as dogs are, and therefore a heartworm infestation is less common in cats and affects them a bit differently. Even so, heartworm is a serious concern for cat owners.

Because a cat is not a perfect host for the heartworm, the worms often don't complete their lifecycle, and therefore do not grow large enough to become a problem or reproduce. However, any surviving worms, and the resulting autoimmune and inflammatory reaction to fend them off, can have severe heath repercussions.

Feline Heartworm Disease

According to Pets WebMD, the small size of a cat's heart means that one or two worms may be enough to cause serious problems. A cat infected with heartworm will often have a persistent cough, breathing difficulty made worse by exercise, weight loss, and lethargy. The cat's autoimmune reaction to the infestation can make the symptoms worse. If the cat survives this stage, he or she will typically be relatively fine for two or three years when the adult worms begin to die. Labored breathing, bronchitis, vomiting and congestive heart disease will often appear in the late stages of the disease and frequently result in death.

Diagnosis, Treatment and Prevention

If symptoms indicate a possible heartworm infestation, your veterinarian can perform lab tests to check for the presence of antigens and antibodies that the body produces to ward off the parasite. X-rays and echocardiography also can show the presence of heartworm disease.

There is no drug or treatment regimen that will cure feline heartworm. Monitoring the disease's progress and offering supportive treatment for cardiac and pulmonary effects is often the best action. Your vet may suggest corticosteroids to lessen the immune reaction to the worms.

The best treatment is of course prevention. Because mosquitoes are the method of infection, keeping your cat away from them is the best prevention. Of course choosing to live where mosquitoes are not as prevalent is not usually an option or even effective. Even indoor cats can get bitten by mosquitoes carrying the parasite. Using a good mosquito repellent can help keep your pet safe. There is also a heartworm medication that you can give monthly during mosquito season (or year around in warm, coastal areas heavily infested with mosquitoes), which, although not always as effective as in dogs, can still help prevent this deadly disease.

Vets at places like Pet Medical Center – Full Service Veterinary Care can assist you.