The Category I mare ( Kenney and Doig 1986): Expected foaling rate 80-90% - fact or fiction?

Summary The subject of the present paper is a critical reflection on the categorization system of Kenney and Doig (1986) which is until now accepted internationally in the histopathological investigation of equine endometrial biopsies. Selected aspects of progress in equine gynecopathology made since 1986 are described and discussed under the view of clinical and prognostic relevance. It was concluded that the categorization neglects important histopathological findings (e.g. angioses, endometrial maldifferentiation) and is therefore incomplete. Beyond this schematized grading which means a reduction of the different findings to an arithmetical code, the biological complexity of etiology, reversibility, and possible interactions of the various alterations is more or less ignored. From the authors´ point of view this is unaccepta-ble from both medical and forensic aspects, especially under the conditions of the new German mercantile law.