The effects of parturition and peripartum complications on the peritoneal fluid composition of mares

Abnormalities in peritoneal fluid are diagnostically useful for managing equine colic; however, their significance in post-dystocia mares is not known. This study was to determine what changes, if any, occurred following obstetrical manipulations. Peritoneal fluid samples were collected from 2 groups of foaling mares to establish control values, and from a third group that had developed clinical abnormalities (CAb,n = 14) or had made an uneventful recovery (CN,n = 36) following fetal extraction. In Group 1 mares, samples were collected before and after induced parturitions (n = 7), and although the total nucleated cell count was increased (P < 0.02) the median values for peritoneal fluid composition remained within the normal reference range. In Group 2 mares, samples were collected after unassisted foalings (n = 10) on postpartum Days 1, 3, 5 and 7, and the peritoneal fluid values remained within the normal reference range. In the Group 3 (CN) mares neither assisted vaginal delivery or fetotomy caused median peritoneal fluid values to rise above the normal reference range. Although remaining within normal limits, the total nucleated cell count was increased (P < 0.01) on Day 2. The median peritoneal fluid total protein value for Group 3 (CAb) mares was greater than the median value for Group 3 (CN) mares on Day 1 (P < 0.05) and Day 2 (P < 0.001). The peritoneal fluid total nucleated cell count in Group 3 (CAb) mares with a uterine tear, vaginal laceration involving the peritoneal cavity, or a ruptured mesocolon was greater than in Group 3 (CN) mares (P < 0.02). The median peritoneal fluid percentage of neutrophils value for Group 3 (CAb) mares was higher than for Group 3 (CN) mares on both Days 1 and 2 (P < 0.02). Elevation of a single peritoneal fluid value in the postpartum mare may be incidental; however, increases in 2 or more of these (total protein > 3.0 g/dl; total nucleated cell count > 15,000 cells/microl; percentage of neutrophils > 80%) is clinically significant.