Effects of blood contamination on equine peritoneal fluid analysis

Peritoneal fluid and blood was collected from 8 healthy adult horses. Four 1-ml aliquots of peritoneal fluid from each horse were then contaminated with 0 ml (normal), 0.05 ml (1 drop), 0.10 ml (2 drops), and 0.20 ml (4 drops) of blood from the same horse. Samples were analyzed for RBC count, nucleated blood cell count, total protein concentration, and nucleated cell differential count. Statistical analysis revealed no significant changes in nucleated cell number, nucleated cell differential, or total protein concentration in peritoneal samples contaminated with blood. The RBC count significantly increased with blood contamination. It was concluded that up to 17% blood contamination of peritoneal fluid in clinically normal horses did not significantly alter interpretation of the nucleated cell count or protein concentration.