Canine heartworms (Dirofilaria immitis) are potentially fatal parasites that infest dogs' cardiovascular and respiratory systems. Infection can be spread by the bite of a single mosquito. Heartworms are a worldwide clinical problem, and in the United States the South historically has the greatest number of cases.
Despite strides in diagnostics, treatment and prevention since its discovery over 100 years ago, heartworm disease continues to be a significant health risk to dogs in the U.S. American Heartworm Society president Wallace Graham attributes this in part to the influence of changing weather patterns on mosquito populations. The Companion Animal Parasite Council points to pet owners not administering heartworm preventatives correctly as the reason for most heartworm infections in the U.S.
Heartworm infections have been reported in all 50 states, with about 1 in 80 dogs affected, according to CAPC. Infections are most prevalent in moist, humid regions along the Atlantic and Gulf coasts, the southeastern states, the Mississippi River Valley and northern California. Capcvet.org offers detailed information about infections rates by county for both dogs and cats.
Number of Infections & Treatments
According to Pets and Parasites, approximately 300,000 dogs in the United States are diagnosed with heartworm disease every year. With very few side effects, topical moxidectin approved for use in heartworm-positive dogs to eliminate microfilariae. Melarsomine dihydrochloride, also called Immiticide, is the drug of choice for eliminating adult heartworms in dogs.
- American Heartworm Society: What Is Heartworm Disease?
- U.S. Federal Drug Administration: Keep The Worms Out Of Your Pet’s Heart! The Facts About Heartworm Disease
- American Heartworm Society: Canine Heartworm Disease
- University of Florida IFAS Extension: Mosquito-Borne Dog Heartworm Disease
- dvm360 News Center: CAPC Statement Addresses Reports of Resistance to Heartworm Preventives in South-Central Region
- CAPC Vet: Canine Heartworm
- dvm360 News Center: Heartworm Disease Diagnosed in Every U.S. State, Veterinary Survey Reports
- Pets and Parasites: Heartworms
Yvette Sajem has been a professional writer since 1995. Her work includes greeting cards and two children's books. A lifelong animal advocate, she is active in animal rescue and transport, and is particularly partial to senior and special needs animals.