Chronic active hepatitis in dogs associated with leptospires.

Chronic active hepatitis was diagnosed in five American Foxhounds from one kennel. Spirochetes were demonstrated in the liver in four of the dogs. A rising titer to Leptospira interrogans serovar grippotyphosa was found in the fifth dog, although spirochetes were not demonstrated in tissues. A serologic survey at the kennel revealed evidence of exposure of 6 of 13 dogs to grippotyphosa. This is the first report of an association between chronic active hepatitis leptospiral infection in any species.