5 Facts Pet Parents Need to Know About Protecting Pets From Heartworms july / august 2025
28
( StatePoint) Heartworms are one of the most common and serious health threats faced by pets. According to the American Heartworm Society, more than a million U. S. pets are infected with heartworms, and incidence numbers are rising— even though heartworms are easily prevented. To equip pet parents to provide the protection their four-legged family members need this summer and year-round, the American Heartworm Society is sharing five vital facts about this deadly threat.
1. A single infected mosquito can spread heartworms to multiple pets. Heartworms aren’ t spread from one pet to another. Instead, they are transmitted when a mosquito feeds on an infected animal, such as a dog, coyote, fox or wolf, then later feeds on other susceptible animals and pets. Within months, heartworms grow from tiny larvae into foot-long adult worms that live in pets’ hearts, lungs and blood vessels.
2. Heartworms are found throughout the United States. Warm, humid locales such as the Gulf States and Southeastern U. S. are widely known as hotbeds of heartworm infection, thanks to the presence of mosquitoes that thrive in these conditions. However, heartworms have become increasingly common in regions such as the Southwest, Pacific Northwest, Upper Midwest and New England. One factor supporting broader transmission is the practice of transporting homeless dogs for adoption from areas of the country where heartworms are extremely common to locales that formerly had few cases. Studies also suggest that mosquitoes prefer feeding on pets with heartworms over pets that don’ t harbor them. Finally, mosquitoes are opportunistic pests that require only small amounts of standing water— including puddles or half-full watering cans— to breed.
3. Heartworms aren’ t just going to the dogs. While dogs are highly susceptible to heartworm infection, cats and ferrets get heartworms, too. One thing all three species have in common is that they can become very ill, and even die, if infected with heartworms. That’ s why the American Heartworm Society recommends heartworm screening and year-round prevention for all pets.
4. There’ s no“ season” for heartworms. While the risk of heartworm spread is greatest for pets from spring through fall,