Heartworm in dogs in Canada in 1988

In late November 1988, 1581 small and mixed animal clinics and institutional veterinarians across Canada were sent a questionnaire in order to assess the status of Dirofilaria immitis in Canada in 1988, and 46% of them responded. Veterinarians reported that 181,577 dogs were blood-tested for heartworm disease and 367 dogs were found with D. immitis microfilariae. Another 60 dogs were amicrofilaremic but diagnosed with heartworm disease to give the total number of cases diagnosed in 1988 as 441 (0.24%).Heartworm was reported from Alberta, Manitoba, Ontario, Quebec, Nova Scotia and New Brunswick, but most (389) of the cases were from Ontario. South-western Ontario continued to be the primary focus of the infection in Canada. There were 22 cases reported from Quebec, mostly from and around Montreal, and 24 from Manitoba, mostly from Selkirk, Winnipeg and surrounding areas. Heartworm was found most frequently in companion dogs over three years of age maintained mainly outdoors in rural areas. About 76% of the cases had a history of not having left Canada, and 24% were observed with clinical signs of heartworm disease.