What are Heartworms?

Heartworms are parasites that cause disease which is usually fatal without proper diagnosis or treatment. Even when diagnosed, treatment for heartworm can be dangerous. Heartworm infection is present throughout mainland Australia and can affect dogs and cats.

What do heartworms look like?

Adult heartworms are long, thin worms that live in the major blood vessels within the lungs and the heart. Some can reach 30 cm long.

How are they spread?

In infected dogs adult heartworm produce a large number of small larvae, called microfilaria. These circulate within the animals bloodstream. When the infected animal is bitten by a mosquito, the mosquito ingests the larvae along with the rest of its meal. Within the mosquito the larvae continue to grow, until they position themselves around the mouth of the mosquito. When the mosquito bites and feeds on the next dog, the larvae enter the skin via the mosquito bite wound. About 12 infective larvae can be transmitted per bite. From there, the larvae continue to grow and migrate through the bloodstream until they reach the large blood vessels around the heart and lungs. Here they reach adult size and produce their own larvae 6 months after the first mosquito bite. The worms interfere with the circulation of blood, damage delicate tissues and cause heart failure. This can result in death.

Can this be treated?

Treating adult heartworm infections is both difficult and risky. Because of the danger involved with treatment and the damage caused by heartworm infection, prevention is much safer than treatment.

Can it be prevented?

Preventative medications can be given as a monthly tablet, monthly spot on, or for adult dogs a convenient yearly injection. (puppies can have the injection but it it given at 12 weeks & 6 months of age)