Is similarity in Major Histocompatibility Complex (MHC) associated with the incidence of retained fetal membranes in draft mares? A cross-sectional study.
Authors: Jaworska Joanna, Tobolski Dawid, Janowski Tomasz
Journal: PloS one
Summary
# Editorial Summary: MHC Similarity and Retained Fetal Membranes in Draft Mares Retained fetal membranes (RFM) remains a significant postpartum complication in mares, occurring in approximately one-third of cases in some populations. One proposed mechanism involves inadequate maternal-fetal immune recognition when mare and foal share similar Major Histocompatibility Complex (MHC) genotypes, potentially preventing proper placental separation; Jaworska and colleagues investigated this hypothesis by genotyping 43 draft mares and their foals using nine MHC microsatellite markers across both MHC Class I and II loci, comparing 14 mares with RFM (failure to expel membranes within three hours postpartum) against 29 controls. Contrary to the immunological hypothesis, no significant differences emerged in MHC compatibility or genetic similarity between mare-foal pairs in the RFM versus control groups, suggesting that MHC matching alone does not explain RFM susceptibility in draft horses. These findings imply that whilst RFM in draft mares may involve genetic predisposition, other mechanisms—such as breed-specific anatomical, metabolic or inflammatory factors—likely play a more prominent role, and practitioners should continue investigating alternative aetiological pathways rather than selecting breeding stock based on MHC dissimilarity as an RFM-prevention strategy.
Read the full abstract on PubMed
Practical Takeaways
- •MHC matching between mare and foal is unlikely to be a useful predictor or management strategy for preventing RFM in draft horses
- •RFM in draft breeds appears to have a different genetic basis than the MHC-similarity hypothesis suggests—focus preventive efforts on other known risk factors
- •The high baseline incidence (33%) in this draft population warrants investigation of breed-specific causes beyond immune incompatibility
Key Findings
- •33% incidence of RFM observed in the studied draft mare population
- •MHC I and MHC II compatibility did not significantly increase RFM risk (P>0.05)
- •No significant differences in MHC genetic similarity between mare-foal pairs with and without RFM (P>0.05)
- •Draft horses may have genetic predisposition to RFM independent of MHC similarity mechanisms