Heartworm, or Dirofilaria immitis, is a parasite spread by mosquitoes. Heartworm largely affects dogs and is present throughout most of Australia, except Tasmania and arid areas. The worms are called heartworms because the adults live in the heart, lungs and blood vessels of an infected dog.
In the early stages of infection there may be no visible signs, but as worms mature in the heart they can cause a physical blockage as well as thickening of the heart and associated blood vessels. This may eventually lead to signs of heart failure and even death.
Heartworm is very easy to prevent with treatment options including annual injection, tablets, chews and spot-ons. If your adult dog has not been on heartworm prevention, a quick blood test is required prior to starting a prevention program. Vaccination is usually the most convenient option and a typical program is as follows:
- Age at 1st vaccination: 3 months
- Age at 2nd vaccination: 9 months
- Age at 3rd vaccination: 15 months, then anually thereafter