Heartworm Disease in Maine - Is My Dog At Risk?


The chickadee may officially be the Maine state bird, but we Mainers know that the real state bird should be the mosquito. Within a few weeks, they'll be out in swarms. Mosquitoes are pests, plain and simple. They make you feel itchy just thinking about them. But mosquitoes are rapidly becoming more of a problem aside from just making us stock up on citronella and anti-itch creams. 

Heartworm disease is a rapidly increasing problem with pets in the U.S. It's seen frequently in the southern part of the country, but within the last decade, heartworm disease has spread into New England as well. Heartworms are parasites that live within an animal's bloodstream, eventually setting up camp within the heart itself, and often spreading to the lungs as well. If left untreated, heartworm disease is fatal.

Heartworm infested heart. Photo from the American Heartworm Society website.

Heartworm infested heart. Photo from the American Heartworm Society website.

How is Heartworm Disease Spread?

A mosquito bites an animal already infected with heartworm and during that bite, microfilaria, or baby heartworms, are ingested by the mosquito where they will mature into larvae over the course of two weeks. Once that mosquito bites another animal, the larvae is left on animal's skin and enters the bloodstream through the bite wound left by the mosquito. They migrate through tissue to enter the bloodstream through blood vessels where they mature into adult worms. It can take up to six months from the time of infection for heartworms to mature into adults. Those adults will take up residence in the heart and lungs


We Live in Maine - What's the Risk of Heartworm?

It's a fact that heartworm disease is more prevalent in the southern part of the country, but it's been found in all fifty states and as far north as Canada. Here in Maine, heartworm disease is becoming more common, and there are several reasons why.


  • Climate - Milder temperatures have caused mosquitoes to show themselves earlier and stay around later in the year.
  • Multiple carriers - Dogs aren't the only species susceptible to heartworm disease. Wolves, coyotes, and foxes can be carriers of heartworm disease.
  • Traveling - Dogs are vacationing with their owners more frequently, and often going into areas where heartworm is rampant. If a dog who is not on heartworm preventatives goes to one of these areas gets infected and returns home, the next mosquito to bite them will then spread heartworm to the next dog that it bites.
  • Rescues - Everyone knows how overpopulated the rescues and shelters are in the southern part of the country. We see a lot of southern dogs making their way to New England to find their forever homes. In some cases, dogs may not be tested for heartworm before they're transferred north. In other cases, they are tested before they leave, but heartworm disease is not detected since the dog may have been recently infected at the time of the test, resulting in a negative result.

What Can I Do to Protect My Dog?

For the cost of treating a 75lb dog for heartworm disease, one can purchase eighteen years worth of preventatives!

For the cost of treating a 75lb dog for heartworm disease, one can purchase eighteen years worth of preventatives!

The easiest, most simple way to protect your dog is by putting them on a heartworm preventative such as Heartgard. Heartworm prevention is very inexpensive in comparison to the cost of treating heartworm disease. In fact, you may have seen our photo on Facebook last year that compared the price of treating for heartworm disease for a 75lb dog. For the same price as treating heartworm disease, your dog could have a lifetime supply of Heartgard with a few extra years added in.

Not only is heartworm disease expensive to treat, but it's no cake walk for the patient either. Treatment involves several injections to kill adult heartworms and strict cage rest for the duration of treatment. As the heartworms die, they can form blood clots, so it's imperative that exercise is limited. If you have a particularly active dog, this can certainly be the biggest challenge of treatment!

It's true that heartworm is more common in the southern part of the United States, but we've recently had some patients test positive for heartworm disease here at BVC and they've never left the state of Maine. Be sure to stop in for your heartworm preventatives and make sure your dog is up to date on their annual heartworm screening!