Heartworm Disease and Cats

Most of us have probably heard of heartworm disease in dogs.  But did you know your cat can also become infected?  Heartworm disease incidence is increasing in both indoor and outdoor cats.  Just like the disease in dogs, it only takes one mosquito bite to infect your cat.  Indoor cats are just as likely to become infected as outdoor cats.  In fact, it is thought indoor cats may be at a higher risk for infection because they have not developed a resistance to infection like outdoor cats have.  

A mosquito bites your cat to cause infection and injects a larval worm into the body.  The worm migrates through the body causing inflammation and damage on the way.  The worm, most of the time, ends up in the heart and associated arteries where it grows into an adult worm approximately the size of a piece of spaghetti.  Rarely the worms can migrate to the skin or brain.  

The clinical signs observed in infected cats vary.  They can range from no signs to severe cardiopulmonary or neurologic conditions.  Most commonly owners report a cough or difficulty breathing (due largely in part to the inflammation caused by larval migration through the lungs), lethargy, chronic and random vomiting.
  

Diagnosis of feline heartworm disease can be performed using a blood test that will detect the presence of the worms actively in the body (antigen) and antibodies that the body produces against the worms.  Other blood work may also be run.  Radiographs to look at the heart and lungs may also be recommended.  Your veterinarian can help recommend appropriate tests and provide interpretation.

Unfortunately there is no safe, approved treatment to eradicate heartworms once your cat is infected.  Your veterinarian can provide medications to help treat the symptoms your cat is experiencing, and in some situations, this may be enough to allow your cat time to clear the infection after several years.  For this reason, monthly heartworm prevention is key to preventing this disease.  Prevention needs to be used monthly even in the winter months because in this area we still have mosquitoes year round, therefore the chance of infection is still possible.  

There are a couple of options available for prevention.  The most common ones are Revolution and Heartgard.  Revolution is a topical application that prevents heartworms, fleas, certain intestinal parasites, and ear mites.  Heartgard is a chewable tablet that prevents heartworms and intestinal parasites.  Consult with your veterinarian about which one is right for you and your cat.