Fecal leukocytes and epithelial cells in horses with diarrhea.

Fecal samples from 74 horses with diarrhea were examined microscopically for leukocytes and epithelial cells. The diarrhea was categorized as either acute (less than two weeks) or chronic, Salmonella positive or negative, and mild or severe (based on the fecal consistency). A large number of fecal leukocytes was strongly suggestive of salmonellosis; however, approximately 1/3 of the horses with Salmonella-negative diarrhea also shed fecal leukocytes. Fecal leukocytes were more common in horses with acute and/or severe diarrhea regardless of cause. Numbers of fecal colonic mucosal epithelial cells were increased in severe diarrhea, and their presence in horses with chronic diarrhea was correlated with salmonellosis. The study supports the concept that fecal leukocytes and epithelial cells occur in increased numbers in equine salmonellosis but also occur in other types of diarrhea.