Page 216 - Canine Lameness

188 13 Carpal Region

(A) (B) (C)

CARPAL REGION

Figure 13.11 Images depict (A, B) radiographic and (C) clinical presentation of a dog with abductor
pollicis longus tendinopathy; (A) osseous proliferation in the area of the radial sulcus visible on the
lateral and (B) craniocaudal radiograph. Also note (C) typical soft tissue swelling associated with this
tendinopathy.

Lack of carpal extension has also been described in dogs with neurologic injury (Holland 2005).
It can occur in dogs with palsy of the distal (antebrachial) branch of the radial nerve. The loss of
radial innervation leads to a lack of ability to extend the carpus and, with continued active flexion
from antebrachial flexor muscles, a progressive loss of carpal extension can occur. This type of loss
of carpal extension is seen in dogs with brachial plexus avulsion (Chapter 16) and in dogs with
iatrogenic transection of the radial nerve.
Lack of carpal flexion while standing and walking is also seen in dogs with severe antebrachial
deformities, a situation described as carpal buckling. A transient loss of carpal extension is
routinely present after limb lengthening (Kwan et al. 2014).
Since full carpal extension is required while standing and walking, loss of carpal extension has a
major clinical impact in dogs. A loss of approximately 30° of extension can make limb use impos-
sible. Lack or loss of carpal extension is diagnosed by observing or videotaping dogs while standing
and walking and using palpation and goniometry. Imaging is performed to identify or rule out
underlying structural disease (in juvenile animals).

13.7.2 Lack or Loss of Carpal Flexion
Since complete carpal flexion is not required for locomotion and to perform activities of daily
living, a loss of carpal flexion has minimal function impact in dogs. Lack of carpal flexion is
frequently present in dogs with carpal osteoarthritis and as a consequence of fractures affecting the
carpal region. Lack of carpal flexion is also present in the majority dogs with antebrachial deformi-
ties secondary to impaired physeal growth. In a case series, 6 of 7 dogs with antebrachial deformi-
ties were lacking carpal flexion with an average loss of flexion of 50° (Marcellin-Little et al. 1998).
The authors have also observed lack of carpal flexion in geriatric, large-breed dogs without identi-
fiable underlying disease.