Indoor Cats At Risk For Heartworm

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Indoor Cats At Risk For Heartworm

Although cats housed indoors have a lower risk for heartworm infection, studies have shown that 25 to 30% of heartworm-infected cats were characterized by their owners as "strictly” indoor cats. 

Read that fact again: 25 to 30% of heartworm-infected cats were characterized by their owners as "strictly” indoor cats. That coupled with the fact that there are no reliable tests for heartworm in cats and the fact that heartworm infestations in cats can be fatal and you have all the information you need to protect your cats against heartworm all year long. 


For heartworm, there was a higher percentage of cats positive for heartworms than dogs in every state except for Arkansas, Louisiana, Mississippi, Oklahoma and Texas. For the 250,000 feline samples and 5 million canine samples, the national averages were 2.7 percent of cats being positive and 1.2 percent of dogs testing positive. In general, three out of every 100 cats tested was positive for heartworm antigen, a good indicator that these positive cats have living heartworms in their lungs, according to the CAPC.

One thought is that these findings could be due to dogs normally being on heartworm preventive while cats are not. 


Labored raspy breathing 
Heart murmur
Irregular heart rhythm


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.



At present, removal of adult worms from cats using an adulticide is not recommended. If a cat is diagnosed with heartworm disease and is asymptomatic, the cat will continue to live with heartworms until the worm’s lifecycle is complete - between two and four years. The published life expectancy for cats with heartworm disease is 1.5 years (median). If the heartworm-infected cat has symptoms associated with heartworm infections, the cat will also need to be treated for symptoms.  


Heartworms are a preventable disease, and there are a number of preventatives that are highly effective and commonly used. Talk with your veterinarian about the right preventive for your indoor cat to protect them against heartworm. It just isn’t worth the risk.

source: Companion Animal Parasite Council
Posted Monday, May 04, 2015