Heartworm Disease in Cats – A Rare but Serious Condition!
14 July, 2016

Heartworm Disease in cats is caused by infestation of the organism, Dirofilaria immitis, a parasite that we refer to as the heartworm. The severity of this disease depends on the number of worms that are present in you kitty, the duration of the infestation, and how your cat responds to the parasite.  Indoor cats are susceptible too as an infected mosquito can easily get into the house and infect the cat.

Heartworm disease is rare in cats

Heartworm disease in cats that haven’t received the right preventative medication is a lot lower than unprotected dogs (approximately one-tenth of the rate of dogs).  Usually, most cats will have only a few heartworms and the worms infecting cats are physically smaller and have a shorter lifespan than those of dogs. Outdoor cats are at increased risk and are twice as likely to contract heartworm disease as indoor cats.

 The symptoms of heart disease

Signs of heartworm infestation in cats include coughing, labored raspy breathing and vomiting. Respiratory problems and vomiting are the predominant symptoms in cases of chronic infestation. A physical examination may also reveal a heart murmur or otherwise irregular heart rhythm.  Occasionally an affected cat may have difficulty walking, experience fainting or seizures, or suffer from fluid accumulation in the abdomen.

Heartworm disease is transmitted to cat when bitten by a mosquito

When an infected mosquito bites a cat, it injects infective larvae into the cat. The larvae migrate and mature for several months, ending up in the right side of the heart and the pulmonary arteries. There they mature into adult heartworms and reproduce about six months from the time they enter the cat. At around eight months after infection, they begin to produce a new crop of microfilaria that will live in the cat’s blood for about one month. Cats’, thankfully, are resistant hosts and few circulating microfilaria are generally found.

Heartworm disease in cats is very difficult to diagnose

There are no specific tests that are able to diagnose heartworm disease in cats. A variety of tests that may be done to aid diagnosis include a urine analysis, heartworm antigen and antibody tests, x-rays which may reveal the enlargement of certain veins or arteries associated with heartworm disease, and an electrocardiograph (ECG), which may allow for identification of worms in the heart or pulmonary artery. An ECG can also exclude or confirm other heart diseases that may exhibit similar symptoms.

There is no treatment for heartworm disease in cats

There really is no effective treatment for heartworm-infected cats. There aren’t any available drugs that really work and cats that seem to be doing well may die suddenly. Treating heartworm infections in cats is risky at best and not treating cats is just as risky. It will take about two years for the parasitic infection to be eliminated in the cat, and serious clinical signs can suddenly appear at any time.  It is also important to note that because heartworms in cats have a much shorter lifespan than those that infest dogs, a spontaneous cure without treatment is more likely to occur.

Prevention is key so that your cat won’t get heartworm disease

Heartworms are a preventable disease and there are a number of medicinal preventatives that are highly effective and commonly used. Your veterinarian can determine which medicine is best for your cat.  It is now recommended that heartworm prevention is given to all cats (even indoor cats) since it is not as easy to diagnose as it is for dogs.  Cats given heartworm prevention drugs have not shown signs of toxicity.

Even though heartworm disease in cats is rare, if you live in a humid climate where mosquitoes are more rampant, start your indoor or outdoor cat on a preventative heartworm medication.

If you have a dog and want to know more about heartworm disease, take a look at our article: Heartworm Disease in Dogs –What You Need to Know!

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