Heartworm is a parasite that uses dogs as a host. When they are immature, the worms (microfilariae) are small and circulate in the blood. Adult worms can grow to more than 12 inches long and live in the heart. An untreated infection leads to congestive heart failure and eventually death.

Signs of heartworm disease can take as long as four-to-seven months to appear after initial infection. However, an infected dog may start coughing within four months of infection. Other signs may include sluggishness, weight loss, and difficulty breathing. A dog that is typically active may become less active.

The degree of infection, the length of time a dog has been infected, and the individual animal’s response to the infection determine just how severe the signs of the disease can be.

If you suspect your dog has heartworm disease, your veterinarian can perform a simple diagnostic blood test. Dogs with heartworm disease can be treated to eliminate adult heartworms inside the dog's heart and lungs, but treatment is costly and potentially dangerous as it involves killing the adult worms inside the dog’s heart. Since the treatment is risky and requires multiple injections, dogs with heartworm disease must be treated at the veterinary clinic. Complete rest is needed for four to six weeks following treatment due to the adult worms dying and needing to be reabsorbed in the blood stream.

By far, the best way to battle heartworm disease is through prevention and usually only costs less than $10/month.

Your dog, any dog, can get heart worm disease, whether he's an "outside" dog or even if he stays inside most of the time. Dogs get heart worm disease from mosquitoes any time of the year. It is the female mosquito that bites and transmits the infection. Female mosquitoes are very tiny and can easily slip through cracks around windows, doors or screens. Every dog can be at risk, indoors or out.

Now that greater numbers of people are traveling across the country with their dogs, on vacation or visiting friends and relatives, no state is entirely heart worm-free. Heart worm disease continues to pose a threat to dogs across the United States. Because heart worm disease is potentially fatal, owners should visit their family veterinarian to learn how easy and convenient prevention can be.

Example: Max, a Golden retriever, lives in a heart worm-endemic state. He has heart worms, but his owners don't know it because the disease is not easily detected until its later stages. Max travels with his owners on vacation to states where there are fewer incidences of heart worm disease like Alaska. While in Alaska, Max is bitten by a mosquito, which picks up the heart worm larvae from his bloodstream. Later, the same mosquito bites a healthy local dog, infecting him with heart worm. The cycle continues.

A problem can also result if a dog from a low-incidence state like Alaska travels into a state where heart worm disease thrives, is bitten by a mosquito and then brings the disease back home.

How can I know for sure if my dog already has heart worm?
The only way to know for sure is to have your family veterinarian examine and test your dog. The procedure is quick and easy. But don't delay in calling your veterinarian to arrange for a heart worm test. If your dog gets heart worm disease, treatment can be dangerous for him and expensive for you.

When is the right time to get my dog tested?
Mosquitoes, the carriers of heart worm disease, can be found at varying times of the year depending on the climate. Ask your veterinarian when the best time is to have your dog tested.

How can I prevent my dog from getting heart worm disease in the future?
If your veterinarian determines that your dog is free of heart worms, he or she will tell you how easy and convenient prevention can be. It's important to follow your veterinarian’s instructions; if you don't, your dog could still be at risk. *Prevention will protect YOUR dog, even if dogs around yours may be positive for heartworm.

ALL dogs should be protected. Now even heartworms are being found in cats. Simple monthly worming (Heartguard Plus, among others, contains medicine that also kill other common worms that dogs pick up in the ground or from your neighborhood.) It is worth the life of your beloved pet.

For additional information on heartworm see www.heartwormsociety.org