Application of digital pathology to assess the effect of hormone treatment on placental histomorphometry in mares with induced ascending placentitis.

This study aimed to evaluate the effects of hormonal treatments with altrenogest (ALT) and estradiol cypionate (ECP) on placental histomorphometry in mares with experimentally induced ascending placentitis, using digital pathology as a quantitative tool. Thirty pregnancies from 27 Criollo-type mares were assigned to six groups: healthy controls (n = 5); basic treatment (n = 5), treated with trimethoprim-sulfamethoxazole (TSM), and flunixin meglumine (FM); ALT group (n = 5) + basic treatment; ECP group (n = 5) + basic treatment; ALT + ECP group (n = 5) in addition to basic treatment; and an untreated placentitis group (n = 5). Following parturition, chorioallantoic samples were collected from the cervical star, uterine body, and both horns. Digital images were analyzed using NIH ImageJ software to quantify microcotyledonary and capillary areas per field. Gestation length in the ECP group was comparable to that of the healthy controls, while placental weight and expulsion time did not differ significantly among groups. Histomorphometric analysis revealed that mares in the ECP group exhibited significantly increased capillary area and total microcotyledonary area compared to other placentitis groups. These results suggest that ECP enhances placental vascularization and microstructure in mares with ascending placentitis. The findings support the therapeutic potential of ECP in promoting placental recovery and maintaining uterine homeostasis. Additionally, this study highlights the utility of digital pathology in the quantitative assessment of equine placental morphology, providing new perspectives for improving therapeutic strategies in the management of placentitis.