Who Is Healthy? A Review of How Equine Control Groups Are Defined in Clinical Orthopaedic Research 1999-2021.

This study undertook a systematic review of case-control and longitudinal studies in equine orthopaedic research, with the aim of uncovering the methods used to define healthy control horses in relation to osteoarthritis and connective tissue conditions, desmitis and tendinitis. The review showed a lack of standardization and consistency in defining and identifying healthy controls, with some studies failing to check for lameness in control animals. This inconsistency could potentially impact the interpretation of research results.

Study Objective and Methodology

• The main objective of this research was to provide a clear definition of the non-invasive methods used for selecting healthy control horses in studies related to osteoarthritis (OA), desmitis, and tendinitis.
• A systematic review was performed, wherein the researchers included case-control studies with a healthy control group and longitudinal studies where horses were required to be healthy at the start. Any studies where joints were visualized using intrusive methods like arthroscopy or post-mortem examination were excluded from the review.

Results of The Study

• From 2,472 OA-focused papers and 2,746 desmitis/tendinitis papers, only 127 and 84 papers respectively met the inclusion criteria.
• For OA-related research, 11 methods were identified for selecting healthy subjects, with most papers using a median of three different methods. The most commonly used methods were dynamic examinations, radiographic evaluations, and clinical examinations.
• For desmitis/tendinitis studies, eight different methods were identified with a typical paper again using three of these. Ultrasonography, along with clinical and dynamic examinations were the most frequently used methods.

Conclusions Drawn

• The studies related to OA and desmitis/tendinitis used comparable methods for identifying healthy horses. However, the way these examinations were performed and deduced varied significantly from study to study. There were instances where lameness in potential control horses was not examined.
• Moreover, the most frequently used methods may not be capable of identifying horses with early onset OA. This could potentially have implications on the understanding and interpretation of results gleaned from these studies.
• The authors suggest that using more sensitive and objective methods to determine health in future control selection, in a standardized manner, could lead to more reliable and consistent results.