The ability of mares to respond to treatment for uterine abnormalities diagnosed by endometrial biopsy and some causes for failure to respond - A review of 1099 cases

Abstract

The records of 1099 mare endometrial biopsy samples were reviewed retrospectively. Samples were submitted for histopathological assessments before and after treatment for acute endometritis or endometrosis or both. Results confirm the remarkable competence of equine uterine mechanisms of defence, regeneration and repair, in that 76-89% of mares who are treated conventionally for acute endometritis resolve these histopathological abnormalities at the first attempt. The most numerous cause of failure to respond to conventional treatments was pneumovagina, caused by poor perineal and vulval conformation, associated with anatomical ageing or immaturity and not correctable by Caslick's vulvoplasty surgery. Four cases were correctable by Pouret's perineoplasty surgery and, in the case of two immature maiden mares, by allowing time for natural perineal maturity to occur. Intrauterine foreign bodies were a cause of persistent acute endometritis in 3 cases. A necrotic placental remnant, a 'lost' swab tip and an infected nidus were responsible. Parturient or coital damage to the equine cervix ended the careers of two broodmares. Translumenal uterine adhesions were a cause of persistent acute endometritis in one case, which was not resolvable. In spite of all efforts, the cause of one case to fail to respond to treatment for acute endometritis remains obscure. The mare repeatedly produced and pooled excessive uterine fluid during early oestrus without bacteriological evidence of primary infection, in spite of treatment for myometrial inadequacy. An endometrial functional abnormality was postulated. This survey also suggests that 75-87% of mares can improve their degree of endometrosis following treatment with endometrial curettage. Therefore, this technique (Ricketts, 1985b) remains a logical option for appropriate cases, where degree of endometrosis is judged to be excessive for age. In contrast to evidence for the development of endometrosis with age (Ricketts and Alonso, 1991a), age of mare did not affect ability to respond to treatment in this series and all ages were represented in both the recovered and failed to recover groups. An accurate diagnosis of equine endometrial disease and its cause is a prerequisite to appropriate treatment and satisfactory recovery. Limiting causes are often extra-endometrial, involving the perineum, cervix, lumenal foreign bodies or adhesions, emphasising the need for thorough complete genital examinations and the need to manage each mare as an indivi dual. Videohysteroscopic examinations are an important diagnostic tool in equine gynaecology, particularly for those mares with persistent endometritis following conventional treatments.