Claire Dixon

Background The sarcoid is the most common equine cutaneous neoplasm. Evidence‐based treatment of this condition is often lacking, and selection of treatment modality based on clinical experience or anecdotal evidence. Objectives To assess the quality of the currently available best evidence regarding the treatment of the equine sarcoid. Study design Systematic review. Methods In compliance with PRISMA guidelines, literature searches were performed in PUBMED, Web of Science, CAB Abstracts, EMBASE (Ovid) and Scopus in April 2021. Included papers were required to describe an interventional study examining sarcoid treatment strategy, of level 4 evidence or greater. The case definition required confirmation of at least some included lesions on histopathology, and a minimum of 6 months of follow‐up was required on treated cases. Studies were assessed by two independent reviewers (KO, CD). Data extraction was performed manually, followed by risk of bias assessment. Methodological quality was assessed using the GRADE system. Results In total, 10 studies were included in the review. Case definition was confirmed via histopathology in all included lesions in 60% of papers. Time to follow‐up was variably reported. Overall risk of bias ranged from ‘some concerns’ to ‘critical’. Reported sarcoid regression rate ranged from 28% to 100% on an individual sarcoid level, and 9%–100% on a whole horse level. Transient local inflammation was reported following most treatment strategies, with further adverse events reported infrequently. Main limitations Review methodology excluded a large proportion of available literature regarding the equine sarcoid. Significant heterogeneity between included studies prevented quantitative synthesis and most included papers were at significant risk of bias, indirectness, and imprecision. Conclusions There is insufficient evidence currently available to recommend one sarcoid treatment over another. There is an urgent need for sufficiently powered, randomised, placebo‐controlled trials in order to allow more definitive comparison of the efficacy of different treatment strategies.