Blastomycosis in dogs: A fifteen-year survey in a very highly endemic area near Eagle River, Wisconsin, USA

Abstract

Purpose A recent study of blastomycosis in dogs has identified an area of high endemicity along waterways in North Central Wisconsin, USA, and suggested a bimodal age distribution of disease. The purpose of this study is to investigate the occurrence and features of dogs with blastomycosis over several years in this area. Methods In June, 1994, a mail survey was sent to 216 owners of properties known to exist within the highly endemic area for blastomycosis west of Eagle River, Wisconsin. Owners were asked to list all dogs kept at that property since 1980, to detail their dogs' demographics and longevity and the occurrence of veterinarian-diagnosed blastomycosis. Features of dogs with and without disease were compared using Epi Info software. Results Seventy-one (33%) of the surveys were returned, and 53 of these properties had housed one or more dogs during this time (87 total dogs). Seventeen (20%) of these dogs had a history of blastomycosis, and 28% of the 53 properties had housed one or more dogs with blastomycosis. All 17 dogs with blastomycosis lived on properties adjacent to or within 100 ft. of the shoreline compared to 76% of dogs without the disease (p = 0.03). Males and purebred dogs were not overrepresented in cases. Seventy-one percent of blastomycosis cases were three years of age or less at diagnosis (average age 3.0 years); 88% had been on the property three years or less until diagnosis, and 59% less than one year (average length 1.9 years). The average length of time on the property for dogs without blastomycosis was 5.7 years (age of ieath, 12.4 years), indicating a significant difference between the two data groups. Conclusions Among dogs in a highly endemic area, young age and recent exposure to the highly endemic parcel and very close proximity to a shoreline are risk factors for blastomycosis.