Heartworm Remains Serious Threat to U.S. Pets

American Heartworm Society survey reveals new incidence trends

APEX, N.C., July 26, 2023 /PRNewswire/ — From Baton Rouge to Boston to San Antonio and Seattle, heartworms pose a serious health threat to the nation’s four-legged family members. According to a recent survey conducted by the American Heartworm Society (AHS), every U.S. state has pets with heartworms. But while states like Louisiana, Mississippi, and Texas have consistently had high heartworm rates, veterinarians participating in the survey reported that infections are also on the rise in unexpected locales like Washington, North Dakota, and Massachusetts.

A survey conducted by the American Heartworm Society found that heartworms are being diagnosed throughout the U.S.

Where mosquitoes go, heartworms follow

Heartworm disease is spread when a mosquito infected with heartworm larvae bites a pet. Once a pet is infected, heartworms cause damage and potentially fatal disease as they grow from microscopic larvae to 12-inch-long worms that live in the pet’s heart, lungs, and blood vessels.

“The good news is that heartworms are almost 100 percent preventable,” said veterinarian and AHS president Dr. Jenni Rizzo. “The bad news is that far too few owners are protecting their pets by giving heartworm preventives year-round.” The AHS monitors numbers of heartworm-positive U.S. pets by conducting periodic surveys of veterinarians who gather heartworm testing data. The AHS recently completed a survey reflecting 12 months’ worth of test results from the 2022 calendar year.

Heartworm numbers rise across the U.S.

Two major findings emerged from the latest AHS survey: (1) heartworm infections continue to increase in areas of the country with historically high rates of heartworm infection; and (2) heartworm rates are also increasing in regions once considered low risk.

According to the AHS, the Southeastern U.S. has long been known for high heartworm rates because mosquito numbers there are high and present year-round. However, thanks to a combination of dynamic weather conditions and the cross-country movement of infected pets, heartworm infection rates have also risen in cold-weather regions like the Northwest, Northeast and Midwest, as well as drier regions like the desert Southwest.

On a more optimistic note, the survey findings revealed an important insight: veterinarians who noted changes in incidence trends in their practice areas all stressed that the key is giving heartworm preventives—and giving them consistently 12 months a year. “When that trend goes up, heartworm incidence goes down,” Rizzo concluded.

For more information on heartworm prevention, testing and treatment, visit heartwormsociety.org.