Peritoneal fluid analysis in equine post-partum emergencies admitted to a referral hospital: A retrospective study of 110 cases

Background Peritoneal fluid analysis has both diagnostic and prognostic value in colic but is little reported in the post-partum mare. Multiple conditions may present similarly in this period, and peritoneal fluid findings may aid a prompt diagnosis. Objectives To describe the peritoneal fluid findings and their association with diagnosis in mares presenting to a single referral hospital for treatment of post-partum emergencies. Study design A retrospective clinical study. Methods Clinical records of 110 Thoroughbred mares were reviewed. Details of peritoneal fluid analysis from samples obtained at admission were recorded, in addition to history, physical examination, presenting clinicopathological data. Cases were classified by their primary diagnosis into groups of gastrointestinal tract (GIT), urogenital trauma (UGT) and post parturient haemorrhage (PPH). Univariable analysis was performed to compare findings between groups, using one-way ANOVA and post hoc Tukey/Kruskal-Wallis, as appropriate. A multinomial logistic regression was performed for variables significant in the univariable analysis. Results When separated into their diagnostic categories, 33/110 (30%) mares were classified as GIT, 55/110 (50%) UGT and 22/110 (20%) PPH. Peritoneal fluid packed cell volume (PCV), nucleated cell count (WBCC) and cytological findings were significantly different between diagnostic categories. The likelihood of diagnosis of PPH increased with an increase in peritoneal fluid PCV, the absence of degenerate neutrophils on peritoneal fluid cytology and a decrease in the peritoneal fluid WBCC. Overall survival to discharge was 55%. Main limitations The study is referral hospital-based and retrospective in nature. Missing data reduced the power of analysis for several variables. Conclusions Peritoneal fluid analysis may guide diagnosis in post-partum emergencies, but no one factor is uniformly diagnostic. Mares with PPH presented with a non-septic peritonitis with higher peritoneal PCV.