Fatal myocarditis in mice fed rancid purified feed.

An outbreak of disease characterized by diarrhea, severe myocarditis, and high mortality occurred in a group of 800 male B6C3F1/ Har mice fed powdered purified diets. A total of 292 animals died. No evidence of an infectious agent was found, and the disease was reproduced in healthy mice by feeding the purified diets, suggesting a nutritional deficiency or toxicity. Analysis of the feed revealed adequate levels of vitamin E, reduced levels of thiamine, and elevated levels of lipoperoxide. It was concluded that mortality was due to myocarditis associated with the ingestion of rancid feed.

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.

Recovery and pathogenicity of several Salmonella species isolated from mice.

Salmonella agona, S anatum, and S oranienburg were isolated from the feces of mice in the course of screening over 4,000 fecal samples from rodents in 22 research and production facilities. The rodents were monitored repeatedly over an 8-month period in 1979-80. These three Salmonella isolates were cultured from mice at 11 of the 22 facilities. Salmonella oranienburg was found in 56% (14 of 25) of Salmonella positive accessions, S anatum in 36% (nine of 25), S agona in 4% (one of 25), and both S oranienburg and S anatum were isolated in one accession. In order to determine the potential pathogenicity of these three Salmonella species, groups of DBA/2N mice were experimentally infected with the three agents. Several animals died acutely of apparent septicemia several days post-inoculation. Mice continued to shed the organisms in the feces for up to 5 weeks post-inoculation at which time they were necropsied and cultured extensively. Culture of visceral organs revealed mice to have systemic dissemination regardless of the Salmonella species. It was concluded that these three Salmonella species were regularly shed in the feces and, although not highly pathogenic, they had the potential to be invasive and cause disease when mice were stressed.

Control of mousepox epizootics in St Louis and Chicago.

In September 1980, mousepox was diagnosed in mice from the Jewish Hospital in St Louis, Missouri. The disease was eliminated by vaccination with vaccinia virus. In October 1980, mousepox was suspected in mice located in an off-campus research facility of the University of Chicago. Based on history, clinical signs, serology, and characteristic pathological lesions, mousepox was diagnosed. The disease was eliminated by killing or moving all mice from the facility. During serological surveillance of mice from other University of Chicago campus facilities, mice from an on-campus facility were found to have positive serological titers and pathological lesions suggestive of ectromelia infection. Some mice in this facility originated from a non-commercial source in which mousepox recently was discovered.