Untreated heartworm infection in pets can be fatal. Heartworm treatment is expensive and lengthy, and only available for dogs (infected cats currently have no options available). The best option for both your pet and you is to prevent an infection.

Mosquitoes carry the heartworm parasite, and one infected mosquito is all it takes. A mosquito can pick up the infection from a lot of different places: cats, dogs, wolves, coyotes, foxes and ferrets are all known hosts to the parasite. If a mosquito bites an infected coyote and then bites your pet, tiny heartworm parasites enter his bloodstream. From there, the worms grow and spread to your pet’s heart and the blood vessels around the lungs. These worms can grow to be up to a foot long.

Heartworm infections have been diagnosed across North America. Your best defense is to maintain a year-round heartworm prevention program. These medicines kill the heartworm larvae before they can infect your pet. The available medicines vary in form (pill, chewable, topical treatments, injections), duration (some last a month, while some last up to six months) and expense, but all are less expensive than treating a heartworm infection. 

Mosquitoes may not be a year-round pest, but having a consistent routine is still best for your pet because the medicines that prevent heartworm infection are effective against only certain larval stages of the parasite.