A report of an outbreak of Salmonella oranienburg in a hybrid mouse colony

Mice in a hybrid breeding colony developed symptoms compatible with a diagnosis of salmonellosis. Salmonella oranienburg was recovered from feces by conventional bacteriological techniques. Active salmonellosis appeared to be precipitated by the stress of pregnancy among breeder female BALB/c mice. Necropsy examination of the BALB/c breeder females revealed diarrhea, roughened hair coats, enlarged spleens, white foci in the liver, and skin abscesses. S. oranienburg was recovered from the spleen, cecum, oropharynx, uterus, and skin abscesses of affected mice. DBA/2N breeder males were asymptomatic and S. oranienburg was recovered from the cecum only. Breeding productivity indices dropped to unacceptable levels in rooms containing infected animals. Relatively normal production was observed among uninfected animals of the same strains in adjacent rooms, thus demonstrating the detrimental effect S. oranienburg had on this breeder colony.