Characterization of leptospirosis among dogs in Oregon, 2007-2011

To characterize the demographics, exposure risks, and outcomes for dogs with leptospirosis in Oregon between 2007 and 2011 and to identify geographic and temporal distributions of known cases of canine leptospirosis within the state during this period.

Retrospective descriptive epidemiological study.

72 dogs.

Reports of laboratory tests for leptospirosis and zoonosis reporting forms voluntarily submitted by veterinarians to the Oregon Health Authority were evaluated to identify dogs with leptospirosis during the study period; data were also collected by examination of medical records or by telephone surveys with veterinarians from reporting facilities.

72 confirmed cases of leptospirosis were identified; surveys were completed for 65 cases. Seasonal and spatial distributions coincided with rainfall patterns for the state, with most cases diagnosed in the spring and in the western part of the state. Common exposure risks included contact with water in the environment (14/65) and contact with wildlife (14); 33 dogs had no history of known exposure risks. Among dogs with other conditions at the time of diagnosis (26/64), dermatitis, otitis, or both were the most commonly reported findings (9/26). Of 65 dogs, 44 recovered, 12 died or were euthanized because of leptospirosis, and 9 were lost to follow-up.

Distribution of canine leptospirosis cases in Oregon fit the rainfall theory pattern. Dermatologic conditions were present in 9 of 64 (14%) dogs that had a diagnosis of leptospirosis; however, further investigation is needed to determine whether such conditions predispose dogs to the disease.