Calcaneal bursitis secondary to intrathecal gastrocnemius and superficial digital flexor tendon tears in two horses

Two horses were referred for acute severe hindlimb lameness that persisted despite rest and nonsteroidal anti-inflammatory drugs. Both cases presented a moderate effusion of the calcaneal bursa (CB) on the medial aspect of the hock of the affected limb. The source of lameness was localised to the CB by intrathecal analgesia. Ultrasonographic examination revealed synovitis of the CB and tearing of the gastrocnemius tendon (GT) in both horses. Additionally, desmitis of the medial retinaculum and a focal area of radiolucency on the plantar border of the calcaneus were also identified in Case 2. Calcaneal bursoscopy was performed under general anaesthesia with the horse in dorsal recumbency. The surgical procedure confirmed the radiographic and ultrasonographic findings and, in addition, revealed the presence of a longitudinal tear of the superficial digital flexor tendon (SDFT) in both cases. During the calcaneal bursoscopy, surgical debridement of the intrathecally torn fibres of the GT and SDFT tendons was performed. Long-term outcome (>24 months) was excellent in both cases. Although uncommon, nonseptic calcaneal bursitis may occur secondary to intrathecal tearing of the GT and SDFT. In these cases, calcaneal bursoscopy may be necessary to obtain a definitive diagnosis and debride torn fibres contributing to the bursitis.