Heartworm disease is most common in dogs, but it can occur in cats with more than 30 other species, including humans – although it is rare.
While the disease can occur in cats, it is different than it does in dogs. Most heartworms do not survive to adulthood in cats, and affected cats usually have only one to three adult heartworms, if not none.
This may seem like a good thing, but it makes heartworm disease difficult to diagnose in cats, and even heartworms that are not yet fully grown can cause something called heartworm-associated respiratory disease.
It is important to understand the causes and symptoms of heartworm disease, as well as preventive measures to keep your cat safe.
Causes of heartworm in cats
Heartworms are transmitted by mosquitoes. They carry the larvae of a host infected with adult female heartworms that produce microscopic babies called microfilariae that move through the bloodstream.
The mosquito carries the microfilariae while they develop to the infectious stage over ten to 14 days. Then the infectious larvae are deposited on the skin of a new host and enter the animal’s bloodstream through the wound caused by the mosquito bite.
Over the next six months, the larvae can grow into adult heartworms. Adults have a lifespan of two to three years in cats.
Symptoms of heartworm in cats
Symptoms of heartworm disease in cats range from mild to severe. They can include:
Difficulty breathing and vomiting are the most common signs in chronic cats.
Cats with heartworm may also develop a heart murmur or an irregular heartbeat. Some cats may have difficulty walking, fainting or seizures.
Sometimes there are no symptoms and the only sign is a sudden breakdown or even death.
Heartworm prevention in cats
Heartworm preventive drugs can be given to cats in the form of an injection, pill, or topical treatment. These drugs work by killing heartworms at the larval stage.
Typically, it is recommended that the oral and topical treatments be given monthly, while the injection is usually given every six months.
It is important to stick to the medication schedule as heartworms mature in just 51 days and must be killed at the larval stage. Preventive drugs do not affect adult heartworms.
Diagnosing and treating heartworm in cats
As mentioned earlier, heartworm disease is different in cats than it is in dogs. There is no specific test for the disease in cats.
Instead, your veterinarian may run a variety of tests to rule out other medical conditions and determine if heartworm disease is causing your cat’s symptoms.
These tests include urinalysis, antigen and antibody tests, x-rays to find enlarged veins and arteries that indicate heartworm disease, or an electrocardiograph that can identify heartworms in the heart and detect other heart conditions that may show symptoms similar to an infestation .
There is no drug that can kill adult heartworms in cats, which is why prevention is so important.
Your veterinarian may suggest surgery to remove adult heartworms, but since heartworms have a relatively short lifespan in cats, your veterinarian may recommend that you stabilize and monitor your cat while it naturally fights off the infection.
Many cats produce enough antibodies to fight off a heartworm infection on their own.
You need to develop a long-term management plan for your cat that includes follow-up visits to your veterinarian. Your veterinarian may prescribe medication to continue treating your cat’s milder symptoms, including steroids or prednisolone to reduce inflammation.
For more severe infections, your cat may need intravenous fluids, medicine for lung and heart problems, antibiotics, or grooming.
If your cat is fighting off the heartworm infection and recovering, it is important that you continue preventive care. Cats that have been infected are already vulnerable, and you don’t want your cat to beat the disease just to get infected again.
Are you keeping up with heartworm disease prevention? Has your cat ever fought off a heartworm infection? Let us know in the comments below!