by Cindy Anderson, DVM
Heartworm disease is a serious and potentially fatal disease in pets in the United States.

Heartworms are caused by foot-long worms (heartworms) that live in the heart, lungs and associated blood vessels of affected pets, causing severe lung disease, heart failure, and
damage to other organs in a dog.

A dog is a natural host for heartworms, which means that the heartworms that live inside the dog can mature into adults, mate and produce offspring. If untreated, the number of heartworms can increase, and dogs have been known to harbor several hundred worms in their bodies.

Heartworm disease causes lasting damage to the heart, lungs and arteries. It also can affect the dog’s health and quality of life long after the parasites are gone. This is why prevention is by far the best option. Treatment, when needed, should be administered as early in the course of the disease as possible.

Heartworm is transmitted by mosquitoes, so warm, muggy areas are certainly hotbeds, but
the infection has been reported in all 50 U.S. states. One bite is all it takes. If a mosquito carrying heartworm larvae bites your dog, those larvae will make themselves at home within your dog, travel to its heart and lungs, and develop into mature heartworms and start reproducing.

Early on, you probably won’t notice any symptoms. But as the number of worms increases, your
dog will develop inflammation in the lungs, and it will probably start coughing or become very
fatigued. If it gets bad enough, your dog can have trouble breathing that could lead to death.

Heartworm also may lead to heart failure, kidney disease, and liver damage, which can cause
bloody or dark urine and a swollen abdomen. Those cases also can become fatal for the dog.

Preventive treatments are incredibly effective, but no preventive is 100% effective. Since
dogs with an early infection may not show symptoms, annual testing is recommended.

Once your dog has a negative heartworm test, it can then be put on a once-per-month preventative medication. The good news is if a dog is on a preventive medication and does test positive, it is unlikely to be infected with a large number of worms. So treatment should be far easier than it would be if the dog was not on any preventive.

Despite the major health risks posed by this disease and the rising number of cases throughout the U.S., a recent study found that only about 30% of dog owners in the United States had purchased heartworm prevention within the last year.

At Lakelands Trail Veterinary Clinic, we recommend a once-a-year test for heartworm and year-round prevention for your dog. If you are interested in preventing heartworm disease in
your dog, we are located at 4525 S. M 52, Stockbridge, MI 49285; or call  517-655-5551.

Cindy Anderson, DVM, is a graduate of MSU Veterinary College (1992) and has practiced veterinary medicine for more than 28 years.