There are many issues dog owners need to be aware of to ensure their pets can enjoy a happy and healthy life. These include diseases, many of which are potentially fatal, but preventable. A common problem for dogs in Hong Kong is heartworm ( Dirofilaria immitis), which is seen in most temperate and tropical zones around the world.

Heartworm is common in northern Australia, but has crept slowly south to affect pets in Australia's southern metropolitan areas. "Here in Hong Kong, heartworm disease is prevalent across the territory, but there are notable pockets, such as Sai Kung, Clear Water Bay, The Peak and Shek O, where there is a much higher prevalence," says veterinarian Lloyd Kenda, of Valley Veterinary Centre

Kenda says he routinely conducts blood tests for heartworm, mainly when a dog has been on heartworm prevention but it has lapsed. "Most pet dogs now test negative for dirofilaria, compared with when I arrived in Hong Kong more than 20 years ago, when I diagnosed and treated many dogs for heartworm disease."

Thanks to client education and prophylactic treatment, the disease is now rare among his clients' pets. "However, like vaccinations, we should not drop our guard, because it is endemic in Hong Kong's wild dogs and, if ignored, it could return in increased numbers," Kenda says.

Heartworm refers to parasitic worms that reside in the dog's heart and lungs. These worms can grow up to 25cm long, Kenda says, and can cause an irritation to the lung tissue, and a physical occlusion (closure or blockage) in the heart chambers. "The blood cannot flow freely through the heart and lungs, and, therefore, the oxygen exchange capacity is reduced."

An infected dog will not show any signs of the disease in the early stages. However, an infection can be detected by a sensitive and specific blood test, Kenda says. As the disease takes hold, the dog will develop a cough and show signs of exercise intolerance. "As more and more worms grow, these symptoms worsen and there can be serious effects on the liver and other body systems," Kenda says.

He says the situation is acute because the disease is spread by mosquitoes, which are plentiful in Hong Kong.

"With a warm, humid climate to encourage the mosquitoes, lots of dogs in close proximity and a few infected dogs that are not treated, heartworm disease is a real risk," he says. "There is enough heartworm in Hong Kong that if your dog is not on preventative medicine, they are at risk of catching the disease."

Kenda adds that heartworm disease can be treated once it is diagnosed, but that prevention is far more preferable. A dog must have a blood test to determine if it is negative for the disease before the owners can contemplate any preventative medication. The test simply requires a few drops of blood, with the result available within minutes. "If the dog is positive, then treatment for heartworm disease is required," Kenda says. "If the dog is negative, then obviously prevention is recommended."

Prevention of heartworm has never been easier.

"Years ago, prevention was in the form of a daily tablet, then came the monthly preventative tablet, but for the past 15 years there has been an annual injection available." There is no excuse for not finding out whether your pet suffers from this awful disease.

"Don't be complacent about heartworm and think, 'It will never happen to my dog'," Kenda says. "Take out a little bit of insurance and have your dog tested and then, if negative, give it the annual preventative injection." 

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