Heartworm Advice Sheet

Heartworms are whit thread-like worms, which grow to 12 - 30 cm long. They live in the heart and the large arteries in the lungs.

Heartworm is spread by mosquitoes. A mosquitoe bites an infected dog drawing up immature heartworms (microfilaria), which are then transmitted into the susceptible dog. The immature heartworm takes 5 months to develop into an adult heartworm. Once a dog has several mature heartworms in its heart the clinical signs od disease develop.

Clinical Signs of the disease are:

- Loss of exercise tolerance.

- Coughing

- Distended abdomen

- Poor coat and illthrift

Diagnosis of heartworm Disease is carried out by a blood test. In most cases a simple smear or concentration test, is used. This test determines the presence of microfilaria. A more sophiisticated blood antigen test may be required at times.

Treatment of Heartworm Disease is quite effective in all but severe cases. It requires the patient to be hospitalised for 2 days whilst injections are given to kill the adult worms. The patient is then checked 1 month after this and if there are no microfilaria present in the blood the patient is started on preventative treatment. Before starting Hertaworm preventative medicine, adult dogs must be checked for the presence of microfilaria in its blood.

Prevention of Heartworm Disease is quite effective in all but severe cases. It requires the patient to be hospitalised for 2 days whilst injections are given to kill the adult worms. The patient is then checked 1 month after this and if ther are no microfilaria present in the blood the patient is started on preventative treatment. Before starting Heartworm preventative medicine, adult dogd must be checked for the presence of microfilaria. A severe and sometimes fatal reaction to the medicine can occur if the dog has microfilaria in its blood.

Prevention of Heartworm Disease is carried out by either administering either an annual injection of PROHEART, a monthly tablet, REVOLUTION DROPS, or a daily tablet of Diethyl Carbamazine (Dimitrol).

There are 3 types of monthly tablets:

Heartgard 30: Heartgard 30 comes as a very palatable chewable cube. Heartgard 30 has no effect on intestinal worms and regular 4 monthly de-worming with Drontol, or CanexMulti Spectrum must be continued.

Interceptor: Interceptor is a flavoured tablet that also eliminates all intestinal worms except tapeworms.Dogs recieving Interceptor need to be dewormed every 6 months for tapeworm using Droncit.

Sentinel: Sentinel is a plain tablet combining Interceptor and Program Flea Control. It prevents heartworm and eliminates all intestinal worms except tapeworms. Dogs receiving Sentinel need to be de-wormed every 6 months for tapeworm using Droncit.

Revolution drops protect against fleas, mange mites, and ear mites as well as Heartworm.

Proheart injection protects only against heartworm and is usually given with the annual vaccination. Proheart stops the worry of giving tablets. No blood test is required before starting Proheart.

Puppies should commence Heartworm preventative treatment at 3-4 months of age. They do not require a blood test before starting heartworm preventative treatment if they are less than 6 months old.

It is best to treat your dog permanently as mosquitoes can be found all year round in most parts of Melbourne. Usual de-worming preparations such as Drontal or Canex Multi Spectrum have no effect on Heartworm.