Heartworm disease is a serious but preventable disease affecting pets Australia-wide. It is caused by the parasite Dirofilaria immitis (heartworm), which is transmitted between pets by infected mosquitoes. 

Adult heartworms up to 30cm long live in the heart and in blood vessels of the lung. They produce offspring called microfilariae, which circulate in the blood of an infected pet and are ingested by biting mosquitoes. Inside the mosquito microfilariae mature to become infective larvae that are transmitted back to healthy pets during subsequent bites.

Once inside a new host the larvae migrate through the body, eventually settling in the blood vessels of the heart and lungs as adult worms which produce microfilariae, and the cycle of infection continues.

In addition to producing microfilariae, adult worms in the blood vessels cause severe damage and lung inflammation. Infected animals demonstrate, over time, a persistent, dry cough, exercise intolerance, weight loss, respiratory distress, abdominal distension, congestive heart failure and death.  

Unfortunately, by the time a pet starts showing signs of disease at least half of their lungs are affected and disease is often advanced. Disease is slowly progressive but eventually fatal. Treatment is costly, difficult and carries risks of its own, including the risk of clot formation around dying heartworms.

Heartworm Disease occurs throughout mainland Australia. Whilst dogs are more commonly affected, cats are also susceptible. Infected mosquitoes do not differentiate by age, sex or breed and all pets are hence susceptible to infection and disease.

Prevention is critical and starts with your puppy or kitten. A range of monthly oral or topical preparations are available, including Heartgard Plus, Revolution, Advocate, Interceptor, Panoramis and Sentinel. An annual injection is also available from your vet. You should choose the method of prevention that is most convenient for you and which, by extension you are most likely to comply with.

If your pet is showing any signs of ill health, is older than 3 months of age and has never been on heartworm prevention, or if there has been a lapse in heartworm prevention to your pet,  please seek the advice of your veterinarian before using a heartworm preventative.