Heartworm Facts Drs. Foster & Smith Educational Staff

The mosquito is the only known vector for transmitting heartworm. The average lifespan of heartworms in untreated pets is 5-7 years in dogs and 2-3 years in cats. Virtually 100% of dogs exposed to infective heartworm larvae become infected; in cats, this number drops to 61% to 90%. Microfilariae are found in the blood of 80%-90% of dogs, while only 20% of cats have these in their blood. Heartworm infection in cats exists everywhere heartworm in dogs exists. The American Heartworm Society (AHS) estimates that only 55% of dogs in the U.S. are currently on a heartworm preventive, leaving 27 million dogs at risk of acquiring heartworm disease. A study performed at North Carolina State University indicated that 25% of cats infected with heartworms were solely indoor cats. Heartworms may infect more than 30 species of animals including coyotes, foxes, wolves and other wild canids, domestic cats and wild felids, ferrets, sea lions, and humans. Prevention is far more effective and less costly than treatment. Research suggests that heartworm disease could be virtually eradicated using available preventives. Heartworms affect cats differently than dogs, but the disease they cause is equally as serious.