Prevention and Care

Dr. Shannon Holland

By Dr. Shannon Holland

14 Feb 2022

Heartworms are a parasite that is spread to dogs and cats by a mosquito’s bite. When the mosquito bites to take a meal the larva that are living inside of an infected mosquito will go into the pet’s blood stream. Over a period of a few weeks the larva will mature into adult heartworms. Then will live in the vessels near the heart that go to the lungs. With a heavy infestation, heartworms will live in the heart as well.

Over time these worms will cause damage to the heart and lungs. If left untreated this will eventually lead to symptoms of cough, trouble breathing, exercise intolerance, heart failure and even death.

The only approved treatment for adult heartworms are multiple injections of a drug called melarsomine. This can be expensive and while generally safe there can be side effects from the injection and from the adult worms dying. Side effects include pain at the injection sites, coughing and pulmonary embolism. Treatment also requires the pet to be calm and quiet for six to eight weeks. This means being confined predominantly to a small cage or room. They can only go outside to go to the restroom and it must be on a leash. In addition, damage caused by heartworms can persist long after the heartworms are gone.

The best way to help our pets with heartworm disease is to prevent it. Heartworm prevention comes in a variety of forms, but all require a prescription from your veterinarian. Your veterinarian can guide you on what prevention type will work best for you and your pet. Heartworm prevention is recommended all year round, even in the winter. Mosquitoes are still present even in the coldest months.

For more information about heartworm disease, treatment and prevention visit the American Heartworm Society website.