Creaturs Corner By Dr. Ted Hankes

Special to The North Jefferson News



Heartworm disease, caused by the infection of a blood-borne parasite called Dirofilaria immitus, infects both dogs and cats.

Infection rates are common nation wide but are much more frequent in southern states due to prevailing warm temperatures and the widespread prevalence of mosquitoes.

Adult heartworms can live for up to five years in the heart and adjacent pulmonary vessels. While living in the heart and pulmonary vessels, they can grow from six to 14 inches long if they are female and three to seven inches long if they are male.

Although infections are extremely rare, people have been infected with adult heartworms. These infections usually occur in a different organ than the heart such as the anterior chamber of the eye.

Heartworms are spread from one animal to another by the bite of mosquitoes. Thirty different species of mosquitoes can transmit heartworms.

While living in the heart, heartworms produce millions of offspring called microfilaria, which live primarily in small blood vessels. Female mosquitoes ingest microfilaria when they bite infected dogs. Microfilaria go through further development while inside the mosquito for approximately the next 20 to 30 days. The microfilaria finally migrate to the mouthparts of the mosquito where they are called infective larvae.

When the female mosquito bites a dog during blood feeding, the infective larvae migrate from the mouthparts of the mosquito into the tissue under the skin. When fully developed, the larvae enter the blood stream where they migrate to the heart and adjacent blood vessels.

Here they will reach the adult stage and begin producing microfilaria. The entire process from the time a mosquito feeds and ingest microfilaria until the adult stage is reached in the heart takes six months. As many as 300 adult worms may live in the heart and adjacent vessels.



Testing for worms

There are two different tests used by veterinarians to determine the presence of heartworm disease. The first test detects the presence of microfilaria in the blood stream and is performed by obtaining a blood sample. The microfilaria can be seen when the blood is examined microscopically.

The second test is also performed by testing a blood sample and actually detects the presence of the adult worms living in the heart. The latter test is more accurate and advanced, as the first test will only detect the presence of heartworm disease if there are actually adult female worms in the heart.

Signs of heartworm infection in dogs and cats are coughing, difficulty breathing, fatigue and poor physical condition.

Cats, unlike dogs, will often vomit. Dogs and cats with heartworm disease can live for quite sometime without showing signs of the disease. Unfortunately damage to the heart and lungs is constantly occurring.



Treatment and prevention

Thankfully, there are several inexpensive monthly medications available from your veterinarian that are effective at preventing this deadly disease.

Once animals become infected, treatment with different much more expensive drugs are required to kill the adult heartworms living in the heart.

This treatment is usually effective depending on how long the animal has been infected, the number of worms present in the heart and how much damage they have already caused. The age of the animal and the overall health of the animal are also significant factors to consider before treating.

An old, well-known adage can be used to highlight the most important information concerning heartworms and your pet. As grandma used to tell us, “an ounce of prevention is worth a pound of cure.”

Dr. Hankes is the owner of Allen Animal Clinic in Gardendale. If you have any questions, concerns, or if Dr. Hankes can be of assistance to you, he can be reached at 631-6210.