Retained fetal membranes in light breed mares hospitalized for attended parturition.

Overview

• This study examined how often retained fetal membranes (RFM) occur in light breed mares after birth, what factors are associated with it, how it is treated, and its consequences.
• The research looked at medical records from a veterinary hospital to identify patterns and outcomes of RFM in these mares.

Background

• Retained fetal membranes (RFM) refer to when a mare fails to expel the placenta fully after giving birth.
• RFM is well-studied in draft breeds but information on light breed mares is limited and contradictory.
• Understanding RFM in light breed mares is important because it can lead to complications such as metritis (uterine infection).

Methods

• The study retrospectively reviewed medical records from 321 light breed mares hospitalized for supervised births at the University of Bologna’s Veterinary Teaching Hospital.
• Data collected included:
  • Breed and age of mares
  • History of previous RFM
  • Parity (number of pregnancies the mare had)
  • Use of assisted reproductive techniques
  • Gestation length
  • Type of pregnancy (normal or high-risk)
  • Use of NSAIDs (non-steroidal anti-inflammatory drugs)
  • Type of parturition: eutocic (normal) or dystocic (difficult)
  • Occurrence of partial or complete RFM
  • Postpartum complications (such as metritis)
  • Treatments provided

Results

• Mares categorized into two groups:
  • Control group (C): 267 mares (83%) who did not experience RFM
  • Retention group (R): 54 mares (17%) who had RFM
• RFM incidence was significantly higher in mares delivering after dystocia (38%) compared to normal parturition (12%).
• Postpartum metritis was much more frequent in the RFM group (59%) versus control (7%), indicating a strong association.
• No significant relationship was found between RFM and other factors such as age, parity, assisted reproduction, NSAIDs use, or gestation length.
• 65% of mares with RFM were successfully treated by intravenous oxytocin administration and uterine lavage (washing out the uterus).
• Other postpartum complications observed included endotoxemia (toxins in the blood), laminitis (hoof inflammation), trauma to the reproductive tract, and gastrointestinal disorders, but all affected mares fully recovered.

Conclusions and Implications

• In light breed mares under supervised parturition at the hospital, RFM was primarily associated with dystocia and subsequent uterine infection (metritis).
• Other potential contributing factors such as electrolyte imbalances were not statistically confirmed but may play a role and require further research.
• Prompt and effective treatment with oxytocin and uterine lavage generally leads to good recovery.
• Findings suggest the importance of monitoring mares with difficult births closely for RFM to prevent serious complications.
• Future studies could explore additional biochemical or physiological factors that might predispose mares to RFM, improving prevention and management strategies.