A subclinical epizootic of sialodacryoadenitis in rats

An epizootic of sialodacryoadenitis was identified in 10-week-old rats 5 days after they were housed with a group of older rats. The young rats generally did not develop the characteristic clinical signs of sialodacryoadenitis, but they did have typical histologic lesions of sialodacryoadenitis in Harderian, lacrimal, and salivary glands. The lesions were variable in distribution and severity, and chronic lesions persisted in the Harderian glands of the rats.