Heartworm Disease, Treatment, and Prevention

Heartworms are parasites that live within the heart and lungs of infected dogs, and occasionally cats
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Transmission-The bite of an infected mosquito transmits the immature heartworm to your pet.  The larva then migrates through the body and eventually finds its way to the heart where it matures into the adult form.  It is within the heart that this parasite reproduces.

Diagnosis-A blood test is used to detect foreign proteins produced by the adult female heartworm.  It is a much better to detect worms BEFORE clinical signs of heartworm disease are present.

Clinical Signs-Signs of heartworm disease may include loss of appetite, weight loss, exercise intolerance, and coughing. In cats, sometimes the ONLY sign is sudden death. Once clinical signs develop, heartworm disease may become life threatening and treatment becomes more difficult.

Treatment-Hospitalization is required for heartworm treatment.  Chest x-rays and blood evaluation are necessary prior to treatment to evaluate the progression of heartworm disease and the patient’s ability to withstand treatment.  For dogs, a drug called immiticide is the current drug of choice used to kill adult heartworms.  The treatment consists of a series of deep injections of this drug into the muscles of the back.  Currently, the ONLY WAY to treat cats with heartworms is to manually extract them from the heart during a surgical procedure. This can also be done for dogs, if they are too sick to survive the injection treatment.  Once treatment has been completed, the patient returns home for approximately 6 weeks of strict CONFINEMENT. Major lung complications may develop if confinement and exercise restriction are not followed during the post-treatment period.  If microfilaria (baby heartworms) are present in the blood at the time of treatment, then the patient returns for one additional treatment 4 weeks later.  The patient will then return 2 weeks after the final treatment and again in 3 months for blood tests to confirm that all heartworms have been killed.

Prevention-The most important aspect of heartworm management is PREVENTION! Several different types of heartworm preventatives are available.  The doctor can discuss the various types of prevention with you, and help you choose the one that is best for your pet.