Effects of intra-articular injections of bufexamac suspension in healthy horses

Objective-To evaluate the effects of intra-articular (IA) Injections of buf examac in horses, focusing particularly on the effects of bufexamac on arti cular cartilage. Animals-20 Standardbreds. Procedure-Horses were randomly allocated into 4 groups consisting of 5 hors es each, and 20, 60, or 100 mg of bufexamac or I ml of sterile saline (0.9% NaCl) solution (control) was Injected into 1 intercarpal joint at weekly I ntervals for 6 treatments (days 0, 7, 14, 21, 28, and 35). Clinical signs a nd results of hematologic, serum biochemical, and synovial fluid (SF) analy ses and radiography were used to evaluate treatment effects. On day 49, all horses were euthanatized; gross necropsy and histologic examinations of in ternal organs and articular tissues were performed. Glycosaminoglycan conce ntration of the articular cartilage was evaluated In safranin O-stained sec tions by use of a semiquantitative microspectrophotometric method. Results-No systemic signs were observed. Temporary mild to moderate heat an d effusion were the only clinical signs observed In a number of joints afte r IA injections and more often only In the 100 mg group, compared with cont rols. The 100 mg dose resulted in significant increases in SF WBC counts, w ith relative neutrophilia and SF total protein concentration 24 hours after injection (day 1). No lesions suggestive of toxic effects were detected at necropsy or on histologic examination. No changes In articular cartilage g lycosaminoglycan concentration were detected. Conclusions and Clinical Relevance-Six Injections of 20, 60, or 100 mg of b ufexamac at weekly Intervals did not cause any untoward systemic or local e ffects. These data suggest that bufexamac is a safe nonsteroidal ant-inflam matory drug for IA administration In horses.