Q: How are heartworm infections treated?

A: Dogs that acquire heartworms can be treated successfully as long as the infection is detected before major damage is done to the heart. After confirming a positive test result, your veterinarian will use a blood filtration test to detect the presence or absence of circulating larval worms, called microfilaria. Before determining a specific treatment protocol, a chest x-ray will also be taken to evaluate damage to the heart or lungs. These steps are important if your veterinarian is to choose the safest and most effective protocol for your specific dog’s disease stage.

Depending on the findings, your veterinarian will perform a single injection or a series of injections to kill the adult worms. The medication is a chemical cousin to arsenic and has a long list of potential side effects. Before initiating treatment, your veterinarian should perform routine health screening blood tests on your dog and discuss all of the potential side effects with you. During the treatments, dogs should be hospitalized for careful monitoring and should have an intravenous catheter in place for rapid emergency treatment should it become necessary. After returning home, dogs must be kept in a crate for at least two full weeks to reduce the risk of dangerous complications.

One month after the initial therapy is completed, dogs should return to the veterinarian for clearance of microfilaria. The doctor will administer an oral dose of another anti-parasitic drug. This medication has considerably fewer potential side effects, but careful monitoring of the pet for the day at the veterinarian’s office is still advised. Three months later, follow-up blood tests can determine the success of both treatments.

Cats that acquire heartworm infection cannot be treated. While not nearly as common as in dogs, cats can be infected with this deadly parasite. I recommend cat owners use a monthly topical spot-on product called Revolution. In addition to preventing external parasites like fleas and ear mites, the product prevents internal parasites like heartworms and intestinal worms.