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Dr. Beth Vesco-Mock
This is a male black shepherd-type dog who has tested positive for heartworms at the Animal Service Center of the Mesilla Valley. He is in need of a home that is willing to take on the heartworm treatment.

So you are probably looking at the picture saying, "Nice-looking dog, but what in the world is heartworms?

Heartworm is a parasite that sets up shop in parts of the heart. Dogs get the parasite from infected mosquitoes. Heartworm disease has been reported in all 50 states, and the bite of just one mosquito infected with the heartworm larvae will give your dog heartworm disease.

Heartworm disease has not only spread throughout the United States, but it's also now found in areas that weren't known to have heartworm issues. Areas like Oregon, California, Arizona and New Mexico, the desert areas where irrigation and building are allowing mosquitoes to survive. If you have mosquitoes and you have animals, you're going to have heartworms. It's just that simple.

The key to understanding heartworms (Dirofilaria immitis) and how they affect your pet's health is to have an understanding of the worm's life cycle. Once this is understood then it will make sense why it is wiser to prevent a heartworm infection than wait and treat the worm once it is present.

The heartworm goes through a total of four molts to mature into an adult worm. The first two occur inside the mosquito and the next two occur inside the final host. So how does the heartworm get into your pet?

Heartworm disease begins with an infected animal, known as the source, that has circulating microfilaria in its blood. A mosquito stops by for a meal and inadvertently sucks up a number of circulating microfilaria in the blood. Once inside the mosquito's body, the microfilaria goes through two molts over 14 days or longer, depending on the environment's temperature. They go through their first two molts and change from an L1 to an L2 and then an L2 to an L3 (third stage of development of the larva).

The L3 is able to migrate into the mosquito's salivary glands, which enables them to burrow into your pet though a mosquito's small bite wound. Once inside an animal (host) where it continues development, the heartworm takes at least six to seven months to go through the last two molts and to become sexually mature before the infection can be detected by a heartworm test.

The heartworms continue to grow in size after reaching sexual maturity (about three months after entering the heart) and the females start to pass microfilaria into the blood. This is why some pets are infected with numerous worms. The mass of twisted and intertwined heartworms in dogs can serve as a significant mechanical blockage to the normal flow of blood. In fact, adult female worms have been known to grow up to 14 inches long; males, meanwhile, are generally shorter.

Think of a garden hose. If pieces of debris block the hose, pressure builds up due to the obstruction of the flow of water.

This is what happens to the heart and blood vessels when more and more heartworms congregate within the right ventricle. The smaller your pet (the host) is, the fewer worms it takes to cause a problem.


This beautiful dog is currently asymptomatic (showing no symptoms) therefore he should be able to handle the heartworm treatment. If you are interested in saving his life (rescue groups have turned him away so his time is limited) and making him a part of your family please stop up to the Animal Service Center of the Mesilla Valley at 3551 Bataan Memorial West to visit him and to start forming that lasting bond.
