Page 214 - Canine Lameness

186 13 Carpal Region

(A) (B) (C)

CARPAL REGION (D)

Figure 13.9 Typical radiographic appearance of an (A, B) angular limb deformity secondary to premature
closure of the distal ulnar physis showing radius procurvatum, valgus deformity, and external rotation of
the distal limb, elbow incongruity, and a shortened ulna. (C) Clinical appearance of (C) carpus varus
secondary to premature radial physis closure, and (D) carpus valgus secondary to premature distal ulnar
physis closure.

13.6 Tendinous and Muscular Lesions of the Carpal Region

Tendon and muscular injuries in the carpal region are sparsely described in the veterinary litera-
ture but, in the authors’ experience, are a more common cause of lameness than previously
thought. These injuries are unlikely to lead to severe disability, and lameness is generally moderate
to mild. Most severe carpal tendon and muscular injuries result from trauma such as shearing
injuries or penetrating wounds (e.g. bite wounds and gunshot wounds). The flexor tendons may be
injured at any level, including caudal to the carpal joint and should therefore be palpated for swell-
ing and pain (Chapter 12).
Flexor carpi ulnaris (FCU) tendinopathy or partial avulsions of the insertion site of the FCU on the
accessory carpal bone occur in dogs, most often in large, athletic dogs. It has been reported in
Greyhounds and a Weimaraner dog (Kuan et al. 2007). The FCU consists of two muscle bellies: the
ulnar head originates from the proximal medial ulna, and the humeral head originates from the
medial epicondyle of the humerus. Both insert as a combined tendon on the accessory carpal bone.
FCU injuries result in a weight-bearing lameness. Upon palpation, a firm swelling is palpable
proximal to the accessory carpal bone. Pain may be exacerbated if the muscle is stretched (e.g.
carpal hyperextension). The diagnosis is confirmed using musculoskeletal ultrasound by seeing a
disruption of collagen fibers and the presence of intratendinous fluid. Radiographs may show