LEPTOSPIRA-INTERROGANS SEROVAR SEJROE INFECTION IN A GROUP OF LABORATORY DOGS

Interstitial nephritis was seen histologically in 19 (59%) out of 32 p ure-breed beagle dogs (16 males and 16 females) subjected to standard safety tests. In these animals no clinical abnormalities were observed and all the tested parameters (haematology, biochemistry and urine an alysis) were within the normal ranges. Leptospiral antibody titres ran ging from 1:100 to 1:6400, against a serovar (hardjo) belonging to the Sejroe serogroup, were detected by the microscopic agglutination test (MAT) in the serum of the 19 dogs with interstitial nephritis. All an imals without renal lesions were seronegative. Leptospiral antigen was detected immunohistochemically in the kidneys of 4 dogs; leptospires were detected in Warthin-Starry stained sections of one dog. Leptospir es were isolated from the kidneys of 3 of the 4 dogs examined by bacte rial culture. The isolated strains were typed as serovar sejroe by res triction endonuclease digestion and Southern blot hybridization analys is of their DNA. It was concluded that Leptospira interrogans serovar sejroe, was responsible for an asymptomatic chronic renal infection wh ich was widespread in this group of laboratory dogs.