Proximal Suspensory Desmitis in the Sports Horse in Forelimbs

Proximal suspensory desmitis (PSD) results in sudden onset lameness, which can be remarkably transient, resolving within 24 hours unless the horse is worked hard. In horses with more chronic injury lameness may be persistent. PSD in forelimbs occurs in horses of all ages and from all disciplines. Extravagantly moving young dressage horses and older upper level competition horses are particularly at risk of injury. Lameness varies from mild to moderate and is rarely severe, unless the lesion is extensive and/or involves the enthesis. Bilateral PSD may result in loss of action rather than overt lameness. Lameness is usually worse on soft ground, especially with the affected limb on the outside of a circle and, when subtle, may be more easily felt by a rider than seen by an observer. Occasionally lameness is only apparent ridden, sometimes with the limb on the inside of a circle. Lameness may not be apparent at the working trot, but may be detectable only at medium or extended trot. Lameness is often transiently accentuated by distal limb flexion. Presumably this is because the suspensory ligament (SL) is relaxed during flexion and is then stretched when the limb is again loaded. In the acute phase there may be slight oedema in the proximal metacarpal region, localised heat and distension of the medial palmar vein, but these features may be transient or absent. Pressure applied to the SL against the palmar aspect of the third metacarpal bone may elicit pain. Forced extension and protraction of the limb may elicit pain.