Heartworm Disease

What is heartworm?

Heartworm disease is a serious and potentially fatal infection involving a parasitic worm, Dirofilaria immitis. Heartworm is spread by infected mosquitoes, which inject a heartworm larvae into a dog when they bite.

After the dog has become infected, the heartworm larvae travel through the blood system, eventually developing into an adult worm in the heart and lungs, causing extensive inflammation and damage. These worms cause significant damage to the cardiovascular system, and can cause life threatening heart failure.

Common signs of heartworm disease include coughing, tiredness and difficulty breathing.

Heartworm prevention

Heartworm is regularly diagnosed in unprotected dogs in Hong Kong, and all dogs should take heartworm prevention medicine. Proheart SR-12 is the best prevention for heartworm. It is an injection that is usually given at the same time as the annual G6 vaccination (see Vaccinations for Dogs), and will prevent heartworm for one year.

Heartworm can also be prevented by using monthly tablets such as Nexgard, Triheart or Heartgard or medication applied to the skin such as Revolution.

Puppies should start taking a heartworm preventative medication before they are 6 months old, and preventative medication should be continued for life.

Heartworm is extremely rare in cats and preventative medication is normally not required.