Distribution of histological lesions in the equine endometrium.

The distribution of histopathological lesions in the equine endometrium was examined to investigate the representativeness of a single biopsy specimen in terms of the whole endometrium. Five sections from each of 110 uteri obtained from slaughtered mares were evaluated microscopically and classified according to a four-category grading system used for endometrial biopsies. Depending on the extent of agreement between the categories of the homologous sections, the uteri were considered to show either good agreement (81 uteri; 73.6 per cent), moderate agreement (26 uteri; 23.6 per cent) or poor agreement (three uteri; 2.7 per cent). All the homologous sections of the group showing moderate agreement were within two adjacent categories. Disagreements were more often due to variations in the distribution of fibrotic lesions than to variations in the degree of chronic infiltrative lesions. There was no seasonal effect on the apparent degree or distribution of lesions. In most cases the examination of a single biopsy, when combined with a thorough clinical examination, should provide adequate information about the condition of a mare's endometrium.