Dog owners urged to take precautions as heartworm cases rise on Island

Dog owners on Prince Edward Island are being encouraged to take precautions to protect their animals from heartworm, as the number of cases takes a big jump. 

"We test about 150 dogs per year for canine heartworm, and in the last about five years we've seen that about 50 per cent of the samples that we get are positive for heartworm," said Dr. Nina Germitsch, a veterinary parasitologist based at the Atlantic Veterinary College in Charlottetown. 

"We've been doing the testing since the '90s and it would be maybe one, two, three dogs a year — sometimes none," she said. "It started increasing in the last 10 years, and really in the last about five years, we've seen a lot of positive cases."

Heartworm disease occurs when an animal hosting the parasite develops inflammation that scars and narrows arteries and damages lung tissue. As well as the heart and lungs, the liver and kidney can also be impaired. 

When a female mosquito bites an infected animal, the parasite's tiny offspring incubate in the insect and eventually get passed on when the mosquito bites another dog. The second dog wouldn't show symptoms until the larvae mature and the adult heartworms start to do damage.

Germitsch said most of the animals that are being diagnosed with canine heartworm on P.E.I. have been imported from the southern United States, part of a flood of rescue dogs being brought into the Atlantic provinces from that region.

She would like to see greater awareness around the potential dangers of the disease so that new owners are better informed and can opt to give their pets preventative medication, usually in the form of chewable pills.

"For parasites in general, there are no rules to import animals into Canada. So there's no restrictions, there's no testing, there's no treatment at all," Germitsch said.

"It's very difficult to diagnose, very difficult to treat," she said — not to mention being very costly.

There are different ways of treating the disease, but Germitsch recommends the protocol from the American Heartworm Society to clinicians, and teaches it to her students.  

"It's a very lengthy treatment. It's a risky treatment, also an expensive treatment," Germitsch said.

"We would give three different drugs… over the course of three months, and then after three months the veterinary needs to give three injections that will actually kill the adult parasite in the heart, to get rid of the parasite in the dog."

The dog's ability to exercise also has to be restricted for up to six months, Germitsch said, to reduce the risk of deadly side-effects like thromboembolism, or blood clots, as the dead parasites are flushed out of the heart. 

Germitsch said the first cases are now being reported in dogs in P.E.I. and New Brunswick that haven't travelled, meaning they contracted the disease locally.