Depending on the degree of degenerative change, horses present with varying degrees of lameness. With advanced disease and in the presence of significant asymmetrical collapse, there may be deformity present in the distal digit.
All breeds can be affected, but horses engaged in Western performance activities may be overrepresented.
Often times, localizing the source of lameness requires intra-articular or regional anesthesia of the digit.
Degenerative disease of the proximal interphalangeal joint as well as fractures of the middle phalanx are seen in most breeds of horses. However horses engaged in western performance activities seem predisposed to injuries involving the proximal interphalangeal joint, especially fractures of the middle phalanx, likely due to the bending and torsional forces generated during abrupt stops and changes in direction.
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Complete radiographic evaluation of the pastern region reveals biaxial eminence fracture fragments affecting the proximal palmar / plantar aspect of the middle phalanx. In addition, there may be varying degrees of malalignment and distal displacement of the proximal phalanx.