Tendinitis of the gastrocnemius tendon is a rare cause of hindlimb lameness in a horse. Injury usually occurs distally, although rarely at the musculotendinous junction. Lameness may be sudden or gradual in onset, and the severity of lameness varies depending on the severity of injury. Distention of the calcaneal (or intertendinous) and gastrocnemius bursa is common. Lameness is usually exacerbated by a proximal limb flexion test.
Lameness is usually improved by perineural analgesia of the tibial nerve, and diagnosis is confirmed with ultrasonography.
Conservative treatment with stall rest and controlled exercise for 6–12 mo is usually indicated. Horses with mild to moderate lesions have a reasonable prognosis for return to athletic work, but the prognosis for horses with more severe lesions is guarded.