It’s easy for a dog to catch heartworm disease: All that it takes is a bite from a mosquito with the infectious heartworm larvae. Mosquitoes are both the means of transmission for heartworms, and a vital step in their mutation. Without mosquitoes, heartworms would be unable to grow to adulthood within dogs. It’s the adult stage of the heartworm that causes the most health implications.
Mosquitoes are difficult to avoid. Although heartworm disease is more common in some areas of the United States, the disease has been reported in every state. Vets recommend that all dogs, regardless of where they live, take year round preventative medicine, which helps ensure that no stray mosquito can pass along heartworm.
Mosquitoes Spread Heartworm
Heartworms cannot travel from animal to animal; mosquitoes spread the parasite. Mosquitoes bite animals – mainly dogs – with microfilaria, or baby heartworms, in their bloodstream. As the mosquitoes bite and feed on the dog, they pass along microfilaria to your pet.
Once within the mosquito's body, the microfilariae incubate and mature. After several days, the microfilariae have matured into a different stage and can be passed along to another dog. In order for the progression to occur within the mosquito, a fairly warm temperature – around 80 degrees or above – is required.
Life Stages of Heartworm
Mosquitoes are a key part of how the heartworm progresses through life. Here are the steps of heartworms' progression to maturity:
1. A mosquito carrying the infectious form of heartworm larvae bites a dog. As the mosquito feeds upon the dog, it leaves the larvae behind in the dog's bloodstream.
2. The larval form of heartworm matures in the dog over the course of several months, turning into the adult form of heartworm.
3. After another three to four months, the adult heartworm can give birth to microfilaria, the young heartworms. At this point, about six or seven months have passed since the first mosquito bite that infected the dog. Only now can the heartworms be detected through tests.
4. When a mosquito bites the dog, the mosquito will ingest the microfilaria.
5. Inside the mosquito, the microfilariae matures over the course of ten to fourteen days, to a larval stage that the mosquito can pass along when biting.
6. The mosquito bites another dog and the cycle starts again.
It’s a fairly simple process for the heartworm to spread. Providing your dog with a preventative medication can stop your dog from getting this dangerous disease, and can also stop the cycle from being passed along to other dogs. Prevention is also helpful because the disease is undetectable for so long, with symptoms that are easily missed, and may not even be indicated by a blood test.
How to Prevent Heartworm in Dogs
Heartworm Tests Explained
This information is for informational purposes only and is not meant as a substitute for the professional advice of, or diagnosis or treatment by,your veterinarian with respect to your pet. It has, however, been verified by a licensed veterinarian for accuracy.