September 17, 2010
Heartworm Disease

This disease is caused by a parasite called Dirofilaria immitis, which lives in the heart and adjacent blood vessels. Its presence in this area causes cardiovascular weakness, compromised lung capacity, and eventual death in some patients. Heartworm disease occurs primarily in dogs, but can occur in cats and other animals on rare occasions.{{more}}

In St. Vincent and the Grenadines I have never found a case of heartworms in cats.

Heartworm is transmitted from dog to dog by mosquitoes. Over 70 species of mosquitoes have already been implicated. Transmission of the parasite occurs as follows: when a female mosquito draws blood from a dog infected with heartworm, it takes with it a number of small immature worms called microfilariae. During the next two – three weeks, the larvae develop within the mosquito into the infective stage. Later, when the mosquito bites a new victim, the disease – causing larvae are injected, and the dog becomes infected.

It takes about six months for the larvae to mature and start producing thousands of new microfilariae inside the circulatory system. The mature worms could attain a length of 14 inches. The adult worms end up occupying the right atrium of the heart, the pulmonary arteries and vena cava, while the microscopic microfilariae circulate throughout the bloodstream.

All these worms within the blood vessels produce an increased workload on the heart, along with restricted blood flow to the lungs, kidneys, and liver, eventually causing multiple organ failure if a progressive severe infestation is left untreated. At first, dogs may exhibit a chronic cough and reduced exercise tolerance, difficult breathing and this may or may not be followed by sudden collapse and death.

Once infected, one dog can easily become a “carrier” or reservoir of infection for an entire neighbourhood. By the time symptoms do occur, the disease is well advanced.

Prevention is preferred to treatment. While there are effective treatments available, we prefer to promote prevention of heartworm disease. Oral and topical medications that are administered monthly are highly effective in preventing heartworm disease.

For further information, contact: Dr. Collin Boyle Unique Animal Care Co. Ltd. Tel: 456 4981