Angioses in the equine endometrium - Pathogenesis and clinical correlations

Abstract

Angioses in the equine endometrium are detectable in varying quality and quantity in nearly 80% of broodmares. Only younger maiden mares have intact vessels, older maiden mares show a mostly mild sclerosis within the intima and the adventitia. In multiparous mares the alterations affect all layers of the vessel walls and resemble the so called "pregnancy sclerosis" in other species. The incidence and degree increases with the number of foals delivered, independent of the age of the mare. At least two factors, age and parity, have to be considered as possible causes for degenerative angiopathies. There seems to be no obviously direct but an indirect negative effect on fertility of the mare, because angioses result in a reduced endometrial perfusion and drainage and the alterations are intimately related to endometrosis. Angioses should be taken into consideration when classifying endometria with a view to prognosis. A relationship between endometrial angioses and extrauterine vascular lesions, possibly leading to fatal hemorrhages during late pregnancy or at foaling and occurring mainly in older mares, is supposed.