Safety of Intra-Articular Gold Microimplants in Horses-A Randomized, Blinded, Controlled Experimental Study

Arthrogenic pain is a common problem in equids. Frequently used treatments such as systemic non-steroidal anti-inflammatory drugs or intra-articular steroids can lead to severe side effects if used repeatedly. Gold has been used since ancient times to treat a variety of conditions and has anti-inflammatory and immunomodulating properties. Results from clinical and in vitro studies suggest that local gold might provide a safe and effective alternative to alleviate articular pain. In particular, gold microimplants have been proposed to this end, but it is unknown if and how healthy joints react to this treatment. The aim of this study was to evaluate the safety of gold microimplants (Berlock-Micro-Implants) mixed with hyaluronic acid and injected into the middle carpal joint of nine healthy horses. Each horse was treated in one carpus and sham-treated on the contralateral. Lameness, carpal temperature increase, swelling, and reactions to joint palpation were observed in both treated and sham-treated carpi in the first week after needle arthroscopy and treatment. Significant differences between treated and sham-treated carpi were found only for mechanical nociceptive thresholds 4 days after treatment. Higher thresholds were found in treated joints compared with sham-treated joints. None of the outcome measures selected in the present study indicated systemic or local adverse effects specifically attributed to gold microimplants. In the absence of systemic and local adverse reactions to gold microimplants, the results of the present study support future clinical trials to test the pain-relieving efficacy of this treatment modality in subacute or chronic articular inflammatory processes in equine patients.