Heartworm Disease: What It Looks Like, How to Treat It, and How to Prevent It

Springtime: the snow is gone, the weather is getting warmer, and the leaves and flowers return. With this, we and our pets get outside, bask in the fresh air, and everything is wonderful. But then something terrible happens. It rains a few times, it gets warmer, and the mosquitoes take over. You mow the lawn; they attack. You sit on your deck; they attack. And just when you think you’ve escaped them on the comfort of your couch, that extra sneaky one buzzes in your ear (I’ll get back to that).

The scariest part of all of this? Tis the season of heartworm transmission.

For those that are unfamiliar with heartworm infection, it is exactly what it sounds like – worms take up residence in the heart and pulmonary arteries. This infection is transmitted by mosquitoes: the mosquito bites an infected dog, ingests the immature stages of the parasite, and transmits the parasite to future dogs through its next bite.

Heartworm infection NEEDS the mosquito in order to be transmitted. Once in the new host, the parasite develops into an adult worm. If both male and female worms are present, they will then produce immature stages, and the cycle continues. Hundreds of worms may be present and they can live up to 7 years.

Signs of heartworm infection in the dog may include a cough, exercise intolerance, decreased appetite, and weight loss. If the infection becomes severe, heart failure can occur resulting in difficulty breathing, pale gums, collapse, enlarged abdomen, and possibly death. Treatment of heartworm disease is lengthy, has additional risks, involves painful injections, and requires STRICT cage rest for 6-8 weeks. Last but not least, it is quite costly. Some dogs even require emergency surgery to remove the worms.

There is a common misconception that this disease only occurs in the South. This is false. While heartworm infection is much more common in the southern states, it has been diagnosed around the world, including all 50 of the Unites States. Over the last six months, I personally have diagnosed FOUR heartworm positive dogs here in the small town of Cambridge, Wisconsin alone.

There is also a misconception that dogs spending most of their time indoors are not at risk. This is also false. Heartworm simply needs an infected dog in the area plus a mosquito. Remember that mosquito buzzing in your ear on the couch? Mosquitoes come inside!!! (I told you I’d get back to that.)

The good news is HEARTWORM DISEASE IS PREVENTABLE! The American Heartworm Association recommends all puppies should be started on year-round heartworm preventative by 8 weeks of age. There are multiple options for effective prevention including several monthly oral or topical products, and these should be discussed with your veterinarian. In addition to monthly preventative, all dogs should be tested annually. The cost of annual testing and prevention is dramatically less than treatment and saves your dog from an often fatal disease. Talk to your veterinarian about what you can do for your dog.

A Word About Cats

Although cats are not the preferred host for heartworm disease, they CAN become infected. Monthly preventatives are safe and effective in cats, and should be discussed with your veterinarian.

See the American Heartworm Society website for more information: Heartworm Basics