Canine Education: Heart Worm Disease

What is Heart Worm Disease? Heartworm disease is a serious and potentially fatal condition caused by parasitic worms living in the arteries of the lungs and in the right side of the heart of dogs, cats and other species of mammals, including wolves, foxes, ferrets, sea lions and (in rare instances) humans. Heartworms are classified as nematodes (roundworms) and are but one of many species of roundworms. The specific roundworm causing heartworm in dogs and cats is known as Dirofilaria immitis.

Adult female heartworms, that may grow to be 14-inches long, living within the infected animal's body, release their young, called microfilarie (pronounced: micro fil ar ee), into their host's bloodstream. The mosquitoes become infected with these microscopic worms after biting into an infected adult animal for a blood meal. During the next 10 to 14 days, the microfilarie mature to the infective larval stage within the mosquito. When the mosquito bites another host (dog, cat or other susceptible animal), the infective larvae enter a new host. It then takes a little over six months for the infective larvae to mature into adult worms that may live for five to seven years (in a dog). The microfilaria cannot mature into adult heartworms without first passing through a mosquito, which is why heartworms occur most often in areas where mosquitoes are a problem.

Within the dog, the time frame between initial infection and growth to adult worms is approximately six to seven months, eventually arriving in the heart and pulmonary vessels where they begin to produce new offspring. This period is referred to as patency.

Is there a Treatment available for Heart Worm? Yes, though the most effective treatment, is PREVENTION. There are many products on the market today that can prevent your

Dog from ever becoming infected with heartworms, such as: Diethylcarbamazine, Macrocyclic Lactone, and Ivermectin. These are commonly found in popular Heart Worm preventives such as: Heartgard^®, Heartgard Plus^®, Merial, Iverhart^TM Plus, Virbac, Interceptor^®, Sentinel, Novartis, Revolution^®, Pfizer. Your vet will need to perform a test to insure that your dog is not infected with Heartworms BEFORE starting any preventives.

Most dogs infected with heartworm can be successfully treated. The goal of treatment is to kill all adult worms and all microfilariae. It is important to try to accomplish this goal with a minimum of harmful effects to the dog, from drugs and the dying heartworms. Heartworm infected dogs showing no signs or mild signs have a high success rate with treatment. Patients with evidence of more severe heartworm disease can be successfully treated, but the possibility of complications and mortality are greater. The presence of severe heartworm disease within a patient in addition to the presence of other life-threatening diseases may prevent treatment for heartworm infection.

Once your dog has completed the heartworm treatment, you will need to keep your dog on the preventives for life, to prevent re-infection.

*This information is not meant to take the place of a Veterinarians advice. This is for educational and informational purposes only and is