Heartworm Prevention

Heartworm Prevention

There are two broad categories of worms that may affect dogs and cats – heartworm and intestinal worms. Please also see our Parasite Control page for more information. In Victoria the risk of heartworm disease in cats is extremely low, and unless you intend travelling to northern Australia with your cat we generally do not recommend routine heartworm prevention for cats.

Heartworm, or “Dirofilaria immitis”, is a blood-borne parasite spread by mosquitoes – ‘carrier’ mosquitoes travel between dogs spreading the disease – so a dog can become infected even if it has no contact with other dogs. It can cause serious and life-threatening illness in dogs, and once infected, treatment can also be dangerous.

Heartworm has a complicated life cycle. Infected dogs have microfilaria, an immature form of heartworm, circulating in their bloodstream. Microfilariae are ingested by mosquitoes when feeding on the blood of infected dogs. The immature parasite develops into a heartworm larva inside the mosquito, then the carrier mosquito can infect the animal. As the worms mature in the heart they can cause a physical blockage as well as thickening of the heart and associated blood vessels. In the early stages of infection there may be no visible signs, however infection can lead to  heart failure and even death. Heartworm is present throughout much of Australia, and each year there are many reported cases of heartworm infection throughout all regions of Victoria. These infections could have been easily avoided by administering regular heartworm preventative medications. And remember foxes are part of the canine family, and can be carriers of heartworm too.

Fortunately, heartworm is very easy to prevent and should form part of your dog’s health care routine. We have very effective preventative treatment options available including monthly tablets, chews, and topical “spot-on’s”. There is also the option for your veterinarian to administer your  dog with an annual long-acting injection. We highly recommend this method as it prevents you forgetting to  give a treatment at home, and we will provide you with a letter each year to remind you of when your pets next injection is due.

Heartworm prevention should be started in puppies at 12 weeks of age, please see Your New Puppy for further information.

If your dog is older than 6 months of age and has not been on heartworm prevention we strongly recommend a heartworm test prior to starting a prevention program, followed by a repeat test 6 months after commencing. This is a blood test that we can perform here at the clinic and with results available in about 5 minutes! Providing the blood test result is negative, we can then discuss the best Heartworm preventative treatment for your dog. If your dog has been on heartworm prevention but missed some doses please contact our staff to work out the best course of action.

Please call us to discuss the best heartworm prevention for your pet.