Retained fetal membranes in light breed mares hospitalized for attended parturition

Retention of fetal membranes (RFM) is well described in draft breeds, whereas data on light breed mares remains limited and inconsistent.

This retrospective study aimed to describe the frequency, associated factors, treatments, and consequences of RFM in light breed mares hospitalized for attended parturition.

Medical records of 321 light breed mares hospitalized for attended parturition at the Veterinary Teaching Hospital, University of Bologna, were retrospectively reviewed. Data collected included: breed, previous history of RFM, age, parity, assisted reproductive techniques, gestation length, type of pregnancy (normal/high-risk), use of NSAIDs, type of parturition (eutocic/dystocic), partial or complete RFM, postpartum complications and treatments.

Mares were divided into Control (C; 267/321 mares, 83%) and Retention (R; 54/321 mares, 17%) groups based on whether RFM occurred after parturition. The frequency of RFM was significantly higher after dystocia (24/63 mares, 38%) than after normal parturition (30/258 mares, 12%) (p < 0.00001). Postpartum metritis was significantly more frequent in the R group (32/54, 59%) compared with the C group (7/267, 7%) (p < 0.00001). Other parameters were not statistically significant. Sixty-five percent of mares were successfully treated with IV oxytocin and uterine lavages. Other postpartum complications included endotoxemia, laminitis, reproductive tract trauma, and gastrointestinal disorders, with all mares achieving full recovery.

In the study population, RFM was associated with dystocia and postpartum metritis. Other contributing factors, such as electrolyte imbalances, warrant additional investigation to better clarify the multifactorial nature of this condition.