Heartworm Disease

Heartworm is a parasitic disease that can affect any dog regardless of age, sex or habitat. It is found in many parts of Australia. Heartworm is spread by mosquitoes, and tends to have a higher incidence in areas heavily populated by mosquitoes. Dogs are considered the most common host for heartworms, however heartworms may also infect more than thirty animal species (including foxes, domestic cats, ferrets) and, rarely, even humans.

What are heartworms?

Heartworms are parasites that live in the blood of a dog’s heart and adjacent blood vessels. They can grow from ten to thirty centimetres in length, reach maturation 6 to 7 months after infection and live for approximately five to seven years. Adult heartworms living in the heart produce offspring, known as microfilariae, which circulate in the animal’s blood. When a female mosquito bites an infected animal, it sucks out the blood containing the microfilariae. When the mosquito bites another pet, the infectious larvae are transmitted. In many cases the infected dog will not show symptoms in the early stages.

Heartworm is the most serious common parasite in dogs because it stresses the dog’s heart by restricting blood flow and also damages other internal organs. The heart may enlarge and become weakened due to an increased workload, and congestive heart failure may occur. Left untreated, the disease can be fatal to dogs.

Blood screening tests can verify the presence of heartworms. Ultrasound and x-rays are used to detect the disease in its later stages. Prompt detection prevents needless suffering.

Heartworm treatment and prevention

The good news is that most dogs with heartworm can be successfully treated, usually with drugs (adulticide, microfilaricide) that kill adult heartworms and their offspring. But prevention is the best solution – it’s safer, much less expensive, and better for your pet!

There are a variety of options for preventing heartworm infection, including an injectable, monthly topicals and monthly chewable or flavoured tablets. Preventative medications are extremely effective and when given properly, on a regular basis, can completely prevent your pet from contracting heartworm.
But remember, year-round or seasonal heartworm protection is as good as your diligence in remembering to give your pet the prescribed medication, as directed by us!

Canine heartworm symptoms include: 

  • • Difficulty breathing 
  • • Coughing
  • • Fatigue, a dog that tires easily
  • • Listlessness
  • • Weight loss
  • • Rough hair coat.


Ask us!

Because of the regional and climate-dependant nature of the heartworm cycle, it is crucial to consult us before giving any medication to your pet. We are your best reference, with expert knowledge of the heartworm cycle and transmission patterns in our region, along with the individual health and activity profile of your dog.
Before starting a preventive program, all dogs that could possibly be affected with mature heartworms should be tested as preventive medicines may cause severe reactions in dogs that are already hosts to adult heartworms. A dog that is on a preventive medicine should be tested routinely to ensure ongoing protection-especially when a dose has been missed or forgotten.
Beware - 'allwormers' sold at supermarkets do not cover for heartworm!