Heartworm Disease by Dr. Mehran Baroughi

What is Heartworm?

Heartworms, Dirofilaria immitis, belong to the same class of worms as roundworms. In fact, they look a bit like roundworms, but that is where the similarity ends. Heartworms spend their adult life in the right side of the heart and the large blood vessels connecting the heart to the lungs. Heartworms are found in dogs, cats, and ferrets. They also occur in wild animals such as coyotes, foxes and wolves. They have rarely been found in people.

How does a dog get Heartworm?

The mosquito plays an essential role in the heartworm life cycle. Adult female heartworms living in an infected dog, fox, coyote, or wolf produce microscopic baby worms called microfilaria that circulate in the bloodstream. When a mosquito bites and takes a blood meal from an infected animal, it picks up these baby worms, which develop and mature into “infective stage” larvae over a period of 10 to 14 days. Then, when the infected mosquito bites another dog, cat, or susceptible wild animal, the infective larvae are deposited onto the surface of the animal’s skin and enter the new host through the mosquito’s bite wound.

What are the symptoms of Heartworm disease?

Signs of heartworm disease may include a mild persistent cough, reluctance to exercise, fatigue after moderate activity, decreased appetite, and weight loss. As heartworm disease progresses, pets may develop heart failure and the appearance of a swollen belly due to excess fluid in the abdomen. Dogs with large numbers of heartworms can develop sudden blockages of blood flow within the heart leading to a life-threatening form of cardiovascular collapse.

Is there a test for Heartworm?

There are few, if any, early signs of disease when a dog or cat is infected with heartworms, so detecting their presence with a heartworm test administered by a veterinarian is important. The test requires just a small blood sample from your pet, and it works by detecting the presence of heartworm proteins. Some veterinarians process heartworm tests right in their hospitals while others send the samples to a diagnostic laboratory. In either case, results are obtained quickly. If your pet tests positive, further tests may be ordered.

Do we have Heartworm in Canada?

Yes. Heartworm occurs in warmer regions, where summer temperatures are high enough for the worm larvae to survive inside the carrier mosquitoes. The high-risk areas in Canada are southern Ontario, southern Quebec Manitoba, and the Okanagan in British Columbia. Heartworm is also found in most states in the US.

How do I protect my dog from Heartworm?

The most common preventatives on the market kill the immature heartworm larvae. As long as they are given to the dog every month (or according to the medication instructions), they are very effective in preventing heartworm infection and subsequent development of heartworm disease. The choice of which preventative to use will be determined by a discussion with your veterinarian and what is best for your pet.

Throughout April & May North Town Veterinary Hospital has special pricing for Heartworm testing! We are also fully equipped to set you up with Heartworm & Parasite protection. With the raise of positive tests we are seeing in our area for Heartworm, fleas, ticks, and other parasites the team at Brampton’s 24hour emergency animal hospital encourages you to make an appointment with us for all your parasite prevention needs.