The intent of this research was to identify if the degenerative changes within arteries in the endometrium (endometrial angiopathies) correlate with degenerative changes in the uterine arteries and can be used as a predictor of increased risk for uterine artery rupture (UAR). With this objective specimens from 20 mares that died from uterine artery rupture and 21 control mares that died from unrelated causes were obtained from cases submitted to the University of Kentucky Veterinary Diagnostic Laboratory (UKVDL) over a two-year period. Postmortem specimens of each mare were collected from the left and right uterine arteries at the origin, bifurcation, and distal to the bifurcation as well as full thickness uterine wall sections at five different sites. An additional sample was taken from the uterine artery at the site of rupture in the affected mares. Tissue samples were immersed in 10% neutral buffered formalin, routinely processed, and stained with hematoxylin and eosin, Masson’s Trichrome, and Verhoeff´s Van Gieson histochemical stains as well as a smooth muscle-actin immunohistochemical marker. Elastosis, fibrosis, and vascular smooth muscle cell degeneration were identified in this study as potential contributors of vascular degeneration and a scoring system was developed to differentiate the degrees of severity of these specific degenerative changes within the intima and media of the vascular wall. Based on the scoring system, sections of uterine arteries and endometrial arterioles were blindly examined and the scored changes recorded for statistical analysis. Although the degenerative changes in endometrial and uterine arteries were similar within each group, the results could not not be used to predict an increased risk for UAR. Furthermore, we determined the major changes in vascular pathology of the affected uterine arteries and show there is a significant difference in degenerative changes between specific layers of the vascular wall.