Prevention of DSL desmitis include regular shoeing/trimming, use of exercise bandages, appropriate training & conditioning of the horse, working in appropriate footing and close observation of a horses’ legs before & after work. Carpal/Tarsal Canal Syndrome Carpal or tarsal canal syndrome is caused by of the soft tissue structures running through the carpal or tarsal canal. It is similar to “carpal tunnel syndrome” in humans. Carpal or Tarsal canal syndrome can be caused by damage to the structures running through the canal (SDFt, DDFt & associated vessels & nerves) or damage to the structures that make up the canal (carpal bones & carpal retinaculum). Acute or repeated trauma to the knee or hock joint, fracture of the carpal or tarsal bones, strain of the digital flexor muscles or tendons, or sprain of the carpal/tarsal ligaments/flexor retinacula over the carpal or tarsal canal by may result in inflammation. Due to the inelastic nature of annular ligaments, any of the above causes will result in the retinaculum acting as a band around the tissues within the canal. This causes inflammation within the canal putting pressure on the nerves, which decreases the function of those nerves, resulting in S&S in the limb innervated by the affected nerve. Blood vessels & tendons will also be affected as they travel through the canal with the nerves. If inflammation becomes chronic there may be fibrosing and thickening of the structures of the carpal or tarsal canal, which may lead to permanent nerve compression even after the initiating injury has been resolved. Horses that are , have a curbed hock, or are affected by bowed tendons, tenosynovitis, chronic carpitis or bog spavin are more likely to develop carpal or tarsal canal syndrome. Horses that exercise wearing knee or hock , or those who hit their knees or hocks through interfering, are also at increased risk for carpal or tarsal canal syndrome. Horses that hyperextend the carpus during strenuous activates are also predisposed. This would include Thoroughbred racers, polo ponies and jumpers. Carpal or tarsal canal syndrome is clinically seen as mild lameness that decreases with rest but increases with work, pain on palpation of the canal, & paresthesia of the limb below the carpus/tarsus with pain along the nerve path that increases with repeated flexion of the carpus/tarsus. Swelling or fibrosis of the affected canal maybe difficult to detect due to the restrictive nature of the ligament. Weak digital pulse, palpable coldness of the affected foot, and synovitis of the affected joint and flexor tendon sheaths may also be noted. Diagnosis of carpal or tarsal canal syndrome is often difficult as the clinical presentation is non- specific and may be mistaken for other joint conditions. Diagnosis can be made through clinical signs and symptoms, palpation, ultrasound and through the elimination of other causes of lameness.
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