Ovum pick-up in mares: Evidence review and best practice recommendations using a modified GRADE approach

Ovum pick-up (OPU) is a procedure that is now performed in mares worldwide to harvest oocytes for in vitro embryo production. There is a lack of consensus surrounding best practices for various procedural elements of the technique and recently there has been an increasing focus on the welfare aspects of the procedure. Our objective was to summarize current practice and to develop guidelines for OPU in the mare, using a modified GRADE approach to optimize efficiency and mare welfare. Published evidence on various aspects of the procedure was compiled, and to supplement the relative lack of publications, a survey was distributed to OPU practitioners on their clinical practice and experience with OPU. This data was reviewed alongside the authors' clinical experience and knowledge. A review of available literature and survey results from 71, predominantly European, respondents representing approximately 9531 OPU procedures over 12 months are described. Best practice guidelines are presented on aspects of the OPU procedure under the headings of mare selection, technical aspects, sedation and analgesia, complications, aftercare and laboratory aspects. Knowledge gaps are highlighted where the evidence was weak and/or insufficient. We conclude that ovum pick-up in mares appears efficient and generally safe when performed in practice, however scientific evidence underpinning several procedural elements is weak particularly related to the optimal analgesic and sedative regimen. This work provides the first international evidence-based recommendations for OPU in the mare and establishes a framework to guide future research priorities, with mare welfare as a central focus.