Dog Heartworm: what is it?

Dog heartworm is a disease common in canines throughout most of the U.S. It is caused by a roundworm (Dirofilaria immitis). The adult worms live primarily in the heart and large vessels of the lungs. The worms can grow to 12 inches or longer in length and live within the chambers of the heart, often extending through the heart valves, prohibiting proper closure.

Results of heartworm infestation are loss of weight, dropsy, chronic cough, shortness of breath, muscular weakness, vision problems, convulsions, heart failure and eventually, death.

How do dogs get heartworms?

Heartworms are transmitted by mosquitoes. Mosquitoes feed on an infected animal pick up the microscopic heartworm larvae. The larvae actually develops in the mosquite and in 2 to 3 weeks reaches a miniature adult stage. As the mosquito feeds on another host, the small adult larvae are deposited on the host dogs skin. These small worms burrow into the dog where they increase in size, travel through the blood stream lodging in the heart where they mature. The entire cycle takes about 9 months.

Treatment
Heartworms can be treated. Although the treatment is safer today than in the past, there is still minimal risk that the animal could die during the treatment process. The treatment for heartworm is a form of arsenic administered at doses intended to kill the worms, but not the dog.

The best treatment is prevention.

Prevention
Prevention is available in convenient monthly doses and acts by killing infective forms of the worm before it has a chance to develop into adult worms. There is now a new 6-month medication available (see your vet for more information on the six-month shot).

In our area heartworm prevention should be used all year not just in spring and summer.

Other Facts

• All dog breeds are susceptible to the infection.
• Heartworms are not a health threat to humans.
• Animals may have heartworms for years before symptoms appear.