Q. What is the heartworm situation here in Maine? Do I need to be concerned?
A. Just like ticks, heartworm was very rare in Maine. Most of the positive dogs moved here from warmer climates with their families. Now there are a couple of changes that are making heartworm more prevalent.
Since 2005 after Hurricane Katrina hit the south, rescues and adoption agencies have been selling dogs to the north. Many of these organizations today are reputable and do appropriate testing for contagious diseases including heart worm. Because of the life cycle of the heart worm, some infected dogs will slip through the cracks. This happens when not all the worms are killed off during treatment, treatment wasn’t completed for any reason, tested negative but were actually positive, or never tested.
Another reason for heartworm taking hold in Maine is the change in our climate. We are having warmer, wet springs and summers which is great weather for breeding mosquitoes, and which are needed to spread heartworm. Mosquitoes are more active in warm, humid weather. If you have standing water collected in buckets, bird baths, and debris, mosquitoes will lay their eggs in the water and the larvae will hatch. Once the females are mature, they will look for blood meals.
Female mosquitoes can bite several times until they are full with food. Then the cycle will start again. Female mosquitoes will take a blood meal from any mammal. If it happens to be a dog that has heartworm with baby heart worms, called microfilariae, in the blood stream, the mosquito will suck up these babies. The babies molt into larvae in the mosquito stomach. When the temperature and humidity is right for successful mosquito populations and warm enough for the heartworm larvae to molt in mosquitoes’ stomachs, the conditions will be right to inject the larvae into a dog.
To help reduce the risk of your best friend getting heart worm, you will need to take several steps. We can’t do much about the weather, but we can change the environment to be less healthy for mosquitoes. Make sure you clean bird baths, pick up yard litter that could collect water, and remove containers, pots, and other vessels that make great homes for mosquitoes. Talk to your neighbors about their standing water, since mosquitoes can travel 1 to 3 miles.
Monthly heartworm medication is recommended. Because folks forget to give the monthly pill if stopped for the winter, the American Heartworm Society recommends using it year-round. There is an injectable heartworm medication that will last six months and one for a year. Though convenient, the problem with the injectable is once given, you can’t take it back. Heartworms are becoming resistant to the preventative medication. It is now recommended to use a bug repellent to prevent mosquito bites. Also, avoid taking your dog outside at dawn and dusk. These are the most active mosquito times.
Judith K. Herman, DVM, CVH
Animal Wellness Center
Augusta, Maine
www.mainehomeopahticvet.com