Owners of rats may become very alarmed when they see their rat has red tears and nasal secretions. Red crusts may also develop around the eyes and nose, and the forepaws may be red from rubbing the face. This redness is not caused by blood, but by the secretion of a red pigment called porphyrin. This pigment is released from a gland behind the eye called the Harderian gland. The scientific name for the colored tears is 'chromodacryorrhea.'
Although the red coloration is not blood, the red tears suggest the rat may have a serious condition because they occur when rats are stressed or ill. If this condition occurs in your rat, try to determine possible stresses and have the rat examined by your veterinarian.