What are Heartworms?

Heartworms are the parasite Dirofilaria immitis. Heartworms can be fatal and are contracted by mosquitoes. The parasite is named as such because they live in the right side of the heart.

What dogs are prone to Heartworms?

All dogs are susceptible to heartworms; however the highest prevalence in the United States is within 150 miles of the Atlantic and Gulf Coast. Male dogss are 4 times more likely to contract heartworms than females. Dogs that live outside are 4 to 5 times more likely to contract heartworms than dogs that live indoors. Higher elevations are less likely to have heartworm breakouts.

Symptoms of Heartworms

Symptoms of Heartworms are not always present, it depends on the size of the dog and the level and maturity of the infestation. The most common symptoms include intolerance to exercise, tiring easily and a coughing. Other symptoms include difficulty breathing, weight loss, spiting up blood, fainting and the skin turning blue or purple.

Diagnosis of Heartworms

To diagnose heartworms a trip to your veterinarian will be required. Your vet will perform blood tests to check for heartworms. The most common test is the heartworm antigen test, which checks for the antigen produced by female heartworms. Another test is the microfilarial concentration test where blood is reviewed under a microscope. Your veterinarian can also do a chest x-ray to look for enlargement of the right ventricle. In more serious cases your vet may want an ECG to get a closer look at the heart.

Treating Heartworms

Treating heartworms is a difficult and dangerous process. Assuming the dog is otherwise healthy and suffering no other side effects from the heartworms such as liver or kidney disease, your vet will likely start a treatment of either thiacetarsamide or melarsomine. These drugs contain arsenic and may have many harsh side effects such as vomiting, diarrhea and kidney failure. Your dog will need to be kept calm and have exercise restricted for a month following treatment to help reduce the risk of dead worms entering the lungs.

Older dogs or dogs with other medical complication who are not eligible for either of these treatments will likely be given a low dose of aspirin daily to help prevent respiratory failure.

In critical situations surgery may be performed to remove the heartworms. This is done through an incision in the jugular vein. A long narrow tool is moved through the vein and into the heart, where the worms are removed one at a time.

Preventing Heartworms

Given the difficulty in treating heartworms, prevention is very important. Puppies can start on a heartworm prevention treatment as early as 6 to 8 weeks of age. Adult dog who have not previously been on a heartworm prevention plan need to have the antigen test completed before starting the treatments. Consult with your vet for the best heartworm preventative for your dog. Another way to prevent heartworm is to protect your dog from mosquitoes. Use an animal friendly mosquito repellent like citronella, and keep your dog inside from late afternoon through the evening when mosquitoes are feeding.