What You Need to Know About Heartworm

04/23/2015 10:10 am ET | Updated Jun 23, 2015

My passion is protecting dogs in all ways -- promoting spay and neuter to reduce the population of unwanted animals, encouraging people to rescue dogs from shelters, and helping them to find a balanced relationship that will make for a happy dog and happy humans.

But I also want to protect dogs from disease, and there’s one killer lurking out there that is silent and invisible. If there are mosquitos in your area, then your dog is at risk. I’m going to share with you what you need to know about heartworm.

While it’s most common on the Atlantic and Gulf coasts and along the Mississippi River and its tributaries, heartworm has been reported in all 50 states. It’s a parasite that spends part of its life cycle in a mosquito. One bite from an infected mosquito can transmit that parasite to your dog, where it develops further. Eventually, it grows into worms that can be up to a foot long, and which will infest your dog’s organs, particularly the heart and lungs.

Luckily, dogs and cats cannot infect each other or humans with heartworm, and they cannot get it by sniffing feces of infected dogs or being around them in the dog park. The mosquito is the only method of transmission, which is why mosquito abatement programs are so important, and why you should never have standing, stagnant water around your property.

From the time of infection, it can be up to six months before your dog shows symptoms. This is why annual testing is so important. Untreated, the condition is fatal. However, while it can be treated, if done in the later stages the process can be very expensive and the follow-up can be difficult. Although I always tell people that dogs need exercise, discipline, and affection, if your dog tests positive for heartworm, then their exercise needs to be restricted until after treatment has been completed, which can take months. During this time, too much physical activity can be deadly.

Even after successful treatment, a dog can be infected again. Heartworm isn’t like the measles, where once you’ve had it you can never get it again. Protection against it is a lifelong need.

To avoid infection, it’s important to have your dogs tested regularly, as well as to prevent the disease in the first place with an ivermectin-based medication. When your dog is taking the proper preventative, any heartworm larva transmitted to them by mosquitos will never develop to the next stage, and never become a threat to your dog’s health or life.

There are rumors that you don’t have to give your dog treatment all year-round if you live where it gets cold, but this is no guarantee. While the larva will not survive in mosquitos if the temperature goes below 57° F (14° C), the mosquito only needs to bite another infected dog to start the cycle all over again. Missing a single dose of heartworm preventative or giving it late can make your dog vulnerable to infection, so it’s not worth the risk.

If you love dogs like I do -- and I know you love your dogs -- the simple step of taking preventative measures now can insure that you’ll avoid this potentially fatal, difficult to treat disease. Remember: a Pack Leader’s job is to provide direction and protection. This is just another way to make sure that your dogs are protected, safe, and happy.