Heartworms in cats is not as common as it is in dogs. However, it is HARD to diagnose and HARD to treat! Cats with heartworms develop a syndrome known as HARD which stands for Heartworm Associated Respiratory Disease.
Heartworms in cats have been found in all 50 United States. Mosquitoes are not picky about where they get their next blood meal. If heartworms in dogs occurs in 1 out of every 89 tested, then we can safely say that infected mosquitoes are biting and exposing cats. Fortunately, cats are more resistant to adult heartworms than dogs. Many cats can rid themselves of these parasites by mounting a strong immune response to heartworms, which causes them to die. Most of the time the developing heartworm dies before it can ever reach the heart.
In cats, less than 25% of developing heartworm larvae actually develop into adult worms in the heart. Whereas, 40-90% of developing heartworm larvae in dogs develop into adult worms. Cats that do acquire adult worms in their hearts usually have fewer and smaller worms when compared to heartworms in dogs. Adult heartworms in cats typically only live for 2-3 years, compared to 5-7 years in dogs.
Although most heartworm larvae do not survive long enough to make it into the heart, these worms cause significant disease in the lungs of cats. Cats develop asthma or allergic bronchitis symptoms. These symptoms are part of a syndrome called Heartworm Associated Respiratory Disease (HARD).
Heartworms in Cats
Clinical Signs: Signs associated with the first stage of heartworm disease (when the worms first enter into the vessels of the lungs) include coughing, difficulty breathing, gagging, and rapid breathing. As the disease progresses, cats can develop vomiting, decreased appetite, weight loss, and decreased activity level. If the heartworm larvae is able to continue to develop into an adult and make it into the heart, symptoms are much more severe and can include collapse and sudden death.
Diagnosis: Heartworm test results can be difficult to interpret in cats. The antigen test is available only detects for adult worms in the heart. This test is often negative because the majority of cats have very few or no adult worms in the heart. There is also an antibody test that helps detect the body’s immune response to heartworms. As stated before, most cats develop a strong immune response against heartworm larvae. Unfortunately, it is difficult to determine if a positive antibody test is from a previous infection that the cat has cleared or an existing heartworm infection.
Treatment: There is currently no treatment available in the United States for cats with adult heartworms. Steroids are commonly used in cats with asthma or allergic bronchitis to help relieve symptoms.
Prevention: There are several oral and topical preventatives that are available for use in cats. These products are recommended every 30 days.[Tweet “There is currently no treatment available in the United States for cats with adult heartworms.”]