Sialodacryoadenitis is an infectious disease of rats caused by rat coronavirus (RCV). Symptoms can vary from the subclinical to death. Most non immune rats do show some degree of illness however. Early signs, especially in very young rats, include squinting, photophobia, lacrymation (runny eyes), and production of porphyrin around the eyes and nose which may also appear on the inside of the forelegs as they attempt to wash themselves. Older rats usually develop sneezing and sometimes swelling of the salivary glands at the angle of the jaw (parotid) and up the sides (submaxillary). Swelling of the Harderian and lacrymal glands around the eyes may also occur.