April is Heartworm Awareness month. You probably know that dogs can be infected with heartworms, but did you know that cats can get heartworm disease, too?
Heartworm disease is different in cats than it is in dogs. While both cats and dogs are infected through the bite of a mosquito carrying heartworm larvae, cats typically only get a few worms, while dogs can harbor hundreds of heartworm larvae.
Heartworm in cats is often undetected because most heartworms in cats die before they reach adulthood, and the standard blood tests to diagnose heartworm only detect adult worms.
Some cats with adult heartworms have mild symptoms, such as vomiting not related to mealtimes or trouble breathing that resembles asthma. Because heartworms act on the cardiovascular system, cats can also die suddenly from pulmonary thromoboembolism or develop congestive heart failure.
How common is feline heartworm infection? In areas of the country where heartworm disease is most common, an antigen study found 10% of cats in shelters had been infected with heartworms. Areas of the country where heartworm disease was less common still found 2% of shelter cats carrying antigens indicating heartworm infection.
Is your area of the country one where there is elevated heartworm danger? The following map from the American Heartworm Society shows the frequency of reported heartworm infections in 2013.
Many people think that keeping their cat indoors is enough protection from heartworm, but a study at North Carolina State University found that 25% of heartworm cases occur in indoor-only cats. Mosquitoes get into your house more often than you realize.
Heartworm in cats does not have a good treatment approach, and a single heartworm can have devastating impact on a cat’s health. The approved medication for heartworm in dogs isn’t safe for cats. As a result, it is recommended that preventative treatment be considered for cats living in areas of the country where heartworms are common, especially if they go outdoors. Your veterinarian can advise you whether a monthly preventative treatment is appropriate for your cat.
Journal American Veterinary Medical Association, Heartworm Infection in Cats: 50 cases (1985-1997)
The Merck Veterinary Manual, Overview of Heartworm Disease
Companion Animal Parasite Council, Feline Heartworm
American Heartworm Society
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