Does Treatment for Heartworms Shorten a Dog's Life Expectancy?

Prevention is the best medicine -- have your dog tested for heartworms and give him monthly medication if he's negative. Images

If your dog tests positive for heartworms, treatment to eradicate them can be tough. Although there's a risk involved in heartworm treatment, there's a greater risk in not taking care of the infestation. Once in a while, a dog succumbs during the course of heartworm treatment. However, he's almost certainly going to have a shortened life expectancy if heartworms are left alone.

The Truth about Heartworms

Dirofilaria immitis, or heartworms, are found throughout most of the United States. Dogs come down with heartworm when bitten by a infected mosquito carrying the parasite's microscopic larvae. If a dog is exposed to infected larvae, it's a virtual certainty he'll come down with heartworm disease. The number of heartworms infecting a dog can range from a single specimen to more than 250, according to the American Heartworm Society. They usually congregate in the heart's right ventricle or the pulmonary arteries. Heartworms can reach a foot in length, living five years or more.

Does Your Dog Have Them?

It takes approximately seven months for larvae to grow to adulthood in a dog's body. In the early stages of infestation, dogs are asymptomatic. As the heartworms grow, affected dogs develop a cough. Symptoms progress to include exercise intolerance and abnormal breathing. Signs of severe heartworm infestation include abnormal cardiac sounds, abdominal fluid accumulation and coma. Dogs might suddenly die.

Treatment Options

The U.S. Food and Drug Administration has approved two medications for heartworm eradication in canines. Thiacetarsamide sodium, an older treatment administered intravenously, can cause numerous side effects in dogs because of its toxicity. A newer drug, Melarsomine dihydrochloride, is injected intramuscularly deeply into the lumbar area.

What's the Prognosis?

Once heartworm drugs are administered, the worms start dying off. The dead worms break into pieces, which can cause a pulmonary blockage in your dog, killing him. It's crucial that dogs undergoing heartworm treatment remain calm and quiet both during the treatment and for months afterward. It's not easy to keep a young dog confined with minimal exercise for long periods, but it's the best way to keep heartworm bits from heading into the lungs. When treatment is over, your dog receives medication to kill off the baby heartworms, or microfilaria.

Heartworm Prevention

A monthly heartworm preventative in tablet form or topically applied can keep your dog free from the travails of heartworm disease. Your vet must take a blood sample to ensure your dog is heartworm-free before prescribing the medication. Depending where you live, heartworm tablets or medications are given seasonally or year-round.