Veterinary Student Michigan State University, College of Veterinary Medicine Grand Ledge, Michigan, United States
Abstract: Background- Gestational diabetes mellitus (GDM) in humans can lead to significant histological and secondary functional placental changes which contribute to fetal hypoxia and growth abnormalities. It is unknown if this occurs in horses. Hypothesis- We hypothesize that the placenta from horses with insulin dysregulation (ID; similar to GDM) will show increased weight, villous abnormalities, and vascular lesions as compared to insulin sensitive (IS) horses. Animals- Ten adult pregnant Arabian mares Methods- Case control study. Placentas were collected immediately after expulsion. The weight and gross characteristics of the placenta were recorded, along with mare reproductive history. Histological samples were collected from predetermined areas of the placenta using a Swiss roll method and were routinely sectioned and stained. Samples were randomized, read blindly and lesions were scored as not present, mild, moderate, or severe (0-3). Endocrine testing was performed on all mares. Comparisons were made between ID and IS mares using Mann-Whitney U tests, Student’s t-tests, and Spearman’s Correlation Coefficients (significant at p < 0.05). Results- There were six IS mares and four ID mares. Mares with ID had more histologic lesions (villous atrophy or immaturity, thickened basement membrane, and vascular changes including proliferation, fibrinoid degeneration, edema, congestion, and hemorrhage; all p values < 0.05) and heavier placental weights (p=0.04) than IS mares. There were no significant correlations between histologic scores and age, parity, or BCS. Conclusions and clinical importance- Findings from this study could support an equine translational model of placental dysfunction as well as guide peri-natal mare and foal care.
