Dystocia and postpartum metritis strongly linked to retained fetal membranes in light breed mares
Background
Retained fetal membranes (RFM) represent a significant postpartum complication in mares, traditionally well-documented in draft breeds. However, comprehensive data regarding its frequency, predisposing factors, and consequences in light breed mares remains limited and inconsistent. This knowledge gap hinders targeted preventative strategies and early intervention protocols for a common and potentially severe condition that can lead to complications like metritis, endotoxemia, and laminitis, impacting mare health and future fertility.
Study Design
This retrospective study analyzed medical records of 321 light breed mares hospitalized for attended parturition at the Veterinary Teaching Hospital, University of Bologna. Researchers collected data on breed, age, parity, previous RFM history, assisted reproductive techniques, gestation length, pregnancy type, NSAID use, and parturition type (eutocic/dystocic). Mares were categorized into Control (C; 267/321 mares) and Retention (R; 54/321 mares) groups based on RFM occurrence. Primary endpoints included RFM frequency, associated factors, postpartum complications, and treatment efficacy.
Results
The study identified a 17% overall frequency of retained fetal membranes (RFM) among the 321 light breed mares. A significant association was found between parturition type and RFM incidence: mares experiencing dystocia had a substantially higher RFM rate (24/63 mares, 38%) compared to those with normal parturition (30/258 mares, 12%) (p < 0.00001). Postpartum metritis was also significantly more frequent in the RFM group (32/54, 59%) compared to the control group (7/267, 7%) (p < 0.00001). Other evaluated parameters, such as age or parity, did not show statistical significance. Treatment with IV oxytocin and uterine lavages proved successful in 65% of affected mares. Other complications observed included endotoxemia, laminitis, reproductive tract trauma, and gastrointestinal disorders, with all mares ultimately achieving full recovery.
The most striking finding was the nearly three-fold increase in RFM risk following dystocia, highlighting a critical period for veterinary vigilance.
Key Findings
- Retained fetal membranes (RFM) occurred in 17% of light breed mares hospitalized for parturition.
- RFM frequency was significantly higher after dystocia (38%) compared to normal parturition (12%) (p < 0.00001).
- Postpartum metritis was significantly more frequent in mares with RFM (59%) vs. controls (7%) (p < 0.00001).
- Treatment with IV oxytocin and uterine lavages was successful in 65% of mares with RFM.
Why It Matters
This study underscores the critical importance of monitoring light breed mares, particularly after difficult births, for retained fetal membranes. Veterinarians and mare owners should be highly vigilant for RFM following dystocia, as it significantly elevates the risk of severe postpartum complications like metritis. The demonstrated efficacy of IV oxytocin and uterine lavages in 65% of cases provides a clear, actionable treatment protocol. While all mares in this study recovered, early detection and intervention are crucial to prevent more severe sequelae, reduce recovery time, and safeguard future reproductive health. Further research into electrolyte imbalances could refine preventative strategies.
retained fetal membranes
mares
dystocia
metritis
equine health
postpartum complications