Both her cats now take a monthly dose of heartworm preventive. Baby and his mother, Mama, were wild strays that the Morrises began to care for in 1993, and they lived primarily outdoors for years. Now, they are mostly indoor animals. Veterinarians say that both indoor and outdoor animals are at risk, since mosquitoes can get indoors. Baby is stable now, but it's difficult for veterinarians to give a prognosis on heartworm disease in cats.
Some cats live with heartworms with no apparent symptoms, while some cats suddenly die.
A North Carolina study found that about 10 percent of cats being treated for heart or lung problems were infected with heartworms. Dogs and cats have different experiences with heartworms. Dogs that get the disease tend to have lots of worms that primarily affect the heart. In cats, the worms most often cause lung problems, and the worms live much less time, about two years. There are two approved heartworm preventives for cats.