Skip to main content


By July 11, 2015 December 18th, 2015 Blog

Mosquitoes! The very thought of them makes me start itching. To our canine and feline friends, mosquitoes represent a much more serious threat than a few itchy bumps. Mosquitoes carry a deadly parasite called the heartworm, which is especially prevalent her in Southeast Texas.

Heartworm disease or dirofilariasis is a serious and potentially fatal disease. It is caused by a blood-borne parasite known as Dirofilaria immitis. This parasite requires the mosquito as an intermediate host before it can complete its life cycle in your pet. As many as 30 species of mosquitoes can transmit heartworms.

Adult heartworms are found in the heart and adjacent large blood vessels of infected dogs. Adult heartworms can grow up to 12 inches in length and life 5-7 years. During this time, the female produces millions of offspring called microfilaria. Adult heartworms cause disease by clogging the heart and major blood vessels leading from the heart. They also interfere with the valve action in the heart. By clogging the main blood vessel, the blood supply to other organs of the body is reduced, particularly blood flow to the lungs, liver and kidneys, causing these organs to malfunction and eventually leading to dealth.

In our feline friends, the worms usually settle in the blood vessels of the lungs. Cats develop more of a lung disease than dogs, complete with respiratory distress and chronic coughing, vomiting or sudden death. There is no single good test for heartworms in cats. And there is no safe treatment. Therefore, prevention is key.

All dogs and cats are at risk, even those animals that live indoors. There may be an indoor-only cat, but there is no such thing as an outdoor-only mosquito! In fact, 1/3 or more feline cases are seen in indoor-only cats.

The good news is that heartworms are easy to prevent. There are flavored heartwom pills or topical liquid preventatives that are administered every 30 days all year-long which provide effective protection against heartworm infection. For dogs there is even a convenient injection that only has to be administered once every 6 months. Many of these products also protect your pet against certain intestinal parasites, such as roundworms and hookworms. In addition, some prevent external parasites such as flease and ear mites.

Puppies and kittens should be started on heartworm preventative at 6-8 weeks of age. Dogs older than 6 months of age should have a sinple blood test done by their veterinarian prior to starting medication. This test only requires a few drops of blood and results are typically available withing 10 minutes.

Southeast Texas has one of the higest incidences of heartworm infection in the United States; but a simple, once a month preventative (or once every 6 months injection) can protect your pet against this deadly parasite.

Leave a Reply