Uterine diagnostics: what is the best sample?

Uterine disease, particularly endometritis, is one of the main causes of infertility in the mare. Effective management of uterine disease requires accurate diagnosis, identification of any infectious agents, and elimination of any predisposing factors. Endometritis cases may be broadly categorised into those which are infectious in origin, such as bacterial or fungal endometritis, or those with a sterile inflammatory process, such as mares that are ‘susceptible’ to persistent mating-induced endometritis. In reality, many mares experience elements of both, with susceptible mares being at a higher risk of developing infectious endometritis. Selecting appropriate sampling techniques and accurately interpreting their findings are essential in guiding case management.

Mares with uterine disease most commonly present as cases of poor fertility, including failure to conceive, pregnancy loss or abortion. Mares with a history of uterine fluid accumulation, abnormal or excessive oedema patterns, or shortened or irregular oestrus cycle lengths are common presentations of uterine disease. Other forms of uterine disease can occur, such as pyometra, post-partum metritis or haemorrhage and, in some cases, can present as acute illness in the mare. This clinical summary focuses on the investigation of uterine causes of poor fertility.