Heartworm Disease in Cats

Heartworm disease is something most dog owners have heard about, and many conscientious owners regularly give their dogs prevention to avoid this condition.  However, many cat owners remain unaware of the disease – even in this modern time, where feline preventative medicine is becoming much more commonly practiced.  Heartworm disease is a complicated problem in the domestic cat, and diagnosis can be tricky.  In addition, therapy is difficult and sometimes dangerous for our feline patients.  This all means that prevention is the best way to manage heartworm disease in cats.  Many owners believe that having their cats indoors protects them from heartworm disease, and this is partially true.  Mosquitoes are the vector for transmission of heartworm disease in both dogs and cats, so indoor cats probably have less exposure to mosquitoes.  However, in Texas we all occasionally see mosquitoes indoors, as no screen door can keep them out 100% of the time.  So, consider prevention for your cat – Revolution or Advantage Multi given monthly can save you and your pet much heartache!

Cats are not good hosts for heartworm disease.  This might make owners feel that heartworm is less dangerous for cats, when in fact the opposite is true.  Cats rarely have patent infections (where mature heartworms are present in the pulmonary vasculature and produce baby heartworms called microfilaria), but the incidence of heartworm infection in cats is approximately 15-20% that of their canine cohorts in a given region.  Cats who are infected often mount an immune response to kill the larvae as they migrate through tissues, long before the worms reach the vasculature and begin to reproduce.  This seems like a good thing, but unfortunately it means that infected cats have much stronger reactions to the presence of the larvae, and the symptoms of the infection are much more severe.  One of the more common presenting complaints caused by heartworm disease in cats is sudden death – a very scary fact.

These radiographs are from a cat with a collapsed right middle lung lobe – later discovered to be from heartworm disease.   There is no way to reinflate the damaged lung lobe, so therapy for this cat will be based on symptom control from now on.  The surrounding lung is likely also damaged from the larval presence, so this cat will need lifelong medication to control his coughing and help him breathe normally.

Please consider prevention for your cat, every month!  Living in Texas means regular exposure to insects of all kinds, during all seasons of the year.  Don’t let your cat contract this preventable and serious disease.  Talk to your veterinarian about the risk in your region and do what you can to protect your feline housemates