Do CATS GET Heartworms?

The answer to this question is an unequivocal "yes". Approximately 15-20 % of cats tested for antibodies to heartworms in Illinois are positive.

The Parasite and it's Migration

The cat is not the normal host for the heartworm which means the migrating larval heartworm is not likely to find its way to the heart should it actually make its way into a cat's skin from a mosquito bite. Mosquitoes that carry heartworm definitely prefer to feed on dogs.

Infected cats typically have less than six adult worms. Because the feline heart and blood vessels are so small, these few worms can cause severe problems in the lungs.

The average length of worms found in feline hearts is only 5-8 inches.

An adult heartworm can expect to live 2-3 years in a cat.

Symptoms of the Disease

The cat's immune system is extremely reactive against heartworms. Symptoms of infection tend to be more immune-related than heart failure related. Cats develop more of a lung disease, complete with respiratory stress, and coughing or vomiting chronically. Feline heartworm disease is often misdiagnosed as feline asthma. Sudden death may occur.

Diagnostic Testing

In order to accurately diagnose feline heartworm disease, two types of blood testing (Antigen, and Antibody) may be needed to evaluate a cat’s heartworm status. This is usually accompanied by chest X-rays or an ultrasound of the heart.

Treatment

The same heartworm adulticide therapy used in dogs may be used in cats but it is extremely
dangerous to do so. There may not be a choice, however, depending on the degree of illness from the heartworm disease. Approximately 1/3 of cats receiving heartworm adulticide therapy will experience life-threatening embolic complications when the worms die suddenly. One month of cage confinement is typically recommended to control circulatory effort after adulticide treatment.

Since the major signs of disease in the cat are due to inflammation and immune stimulation, a medication such as prednisone is used to control symptoms.

In general, if the cat does not appear sick, the American Heartworm Society recommends attempting to wait out the worm's 2-3 year life span and monitor chest X-rays every 6 months.

Prevention

Preventive medication is available and recommended for all cats living in geographic areas where the disease is prevalent, such as the eastern and Midwestern states, and California.

Revolution - This is a revolutionary new product that will prevent heartworm infection as well as prevent and treat ear mites, roundworms, hookworms, and fleas. It is applied topically once a month. This is recommended for all cats (especially in/outdoor cats) and may be started at 6 weeks of age.

Heartgard is a once a month chewable medication to prevent heartworm infection and may be started at 6 weeks of age. This is recommended for all cats(especially indoor cats) and may be started at 6 weeks of age.

The reasons that your cat needs to be on heartworm prevention:

1. Diagnostic Difficulty. Diagnosing heartworms is not as easy in cats as in dogs. Often, radiographs or ultrasound studies are needed to confirm the diagnosis. Many cats are diagnosed with an autopsy following sudden death.
2. Unknown Incidence. As we look more aggressively for heartworms in cats with better and better
   tests, we expect to find that the incidence is greater than previously thought.
3. No Good Treatment. Effective drugs are not available, and cats that seem to be doing well may die suddenly. Treating heartworm infections in cats is risky, and not treating these cats is just as risky.
4. Prevention Is Safe and Easy. Cats can be given heartworm prevention drugs orally or topically. There is a wide margin of safety, even in kittens as young as six weeks of age.
5. Indoor Cats Get Heartworms, Too. Exposure to mosquitoes is required for transmission. Cats do not have to be exposed to cats or dogs infected with heartworms. Obviously, cats that go outdoors are more likely to be exposed; however, about 1/3 to 1/2 of cats that are diagnosed with heartworms are reported by their owners to be indoor only. This simply means that mosquitoes that come into the house are just as dangerous as the ones outdoors.