Cytologic interpretation of peritoneal fluid in the evaluation of equine abdominal crises.

Cytologic examination of serial peritoneal fluid samples of nine experimental ponies was performed during a 72 hour period following laparotomy. Six of the ponies had jejunal infarction induced by occlusion of the corresponding vasculature. Cytologic examination was also performed on the peritoneal fluid of a series of horses with naturally occurring abdominal crises presented to the Large Animal Clinic. A rapid staining technique allowed evaluation of smears within 5 minutes of obtaining the fluid. Alterations in peritoneal fluid of the experimental and clinical cases reflected an acute inflammatory response. In the experimental ponies, the degree of degenerate changes in the neutrophils varied considerably between the ponies with induced jejunal infarction and the controls. Extracellular bacteria and a severe degenerative inflammatory response in the peritoneal fluid of the experimental ponies and horses with naturally occurring abdominal crises provided a grave prognosis for survival. The ease of performing cytologic examination of peritoneal fluid and the potential value of the findings supports routine diagnostic use.