A Heartworm Test? Why?

Before starting a parasite preventative, all dogs should be tested for heartworms for several reasons.

  • Giving certain types of preventatives to dogs that have an adult heartworm infection can be harmful or even fatal to the pet.
  • Heartworm preventatives do not kill the adult heartworms (although they may shorten the worms’ life expectancy). This means an infected dog will remain infected with adult heartworms.
  • Unfortunately, as long as a pet remains infected, heartworm disease will progress and damage your pets heart and lungs, which can lead to life threatening problems. Giving heartworm preventatives to heartworm-positive dogs can mislead an owner into thinking everything is all right, while within a pet, heartworm disease is worsening.
  • The parasite preventative that we recommend, Heartgard, only kills existing immature heartworms introduced to your dog over the past 30 days. The active ingredient in Heartgard, Ivermectin, is out of your pet’s system in 24-48 hours. If your pet was exposed to heartworm disease by an infected mesquito over 30 days ago, those worms will continue to mature.
  • Below is an illustration to better explain what can happen if you start a heartworm preventative without testing first.

heartworm testing



















What exactly is heartworm?

Heartworm (Dirofilaria immitis) is a parasitic roundworm that is spread from host to host through the bites of mosquitoes. The heartworm is a type of filaria, a small thread-like worm, that causes filariasis. The definitive host is the dog, but it can also infect cats, wolves, coyotes, foxes and other animals, such as ferrets, sea lions and even, under very rare circumstances, humans. The parasite is commonly called “heartworm”; however, adults often reside in the pulmonary arterial system (lung arteries) as well as the heart, and a major effect on the health of the animal is a manifestation of damage to the lung vessels and tissues. Occasionally, adult heartworms migrate to the right heart and even the great veins in heavy infections. Heartworm infection may result in serious disease for the host, with death typically as the result of congestive heart failure.

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