Front Matter

Chapter 12 Disorders of the Canine Thoracic Limb: Diagnosis and Treatment 305

The shoulder abduction test (Cook et al.,
2005a), although originally described with
patients under sedation in lateral recumbency,
may be performed with similarly consistent
results on awake and standing patients. A goni­
ometer is held with its stable arm parallel to the
spine of the scapula, the center of rotation over
the shoulder joint, and its free arm extending
over the axis of the humerus in contact with the
skin. With the elbow and shoulder held in exten­
sion, the thoracic limb is abducted to its physio­
logical limit and the measurement obtained as
shown in Figure 12.13. The same technique is
applied to the contralateral shoulder for compar­
ison. Using this palpation technique, it has been
reported that a normal mean shoulder abduction
angle is approximately 30 degrees (Cook et al.,
2005a). Although this report revealed that dogs
with medial shoulder instability had abduction
angles significantly larger than 30 degrees, a

more recent study showed an inconsistent corre­

lation between abduction angles and medial

compartment pathological changes identified

arthroscopically (Cook et al., 2005a; Devitt et al.,

2007). Patients with MSS rarely show evidence of

instability but rather show signs of dysfunction

and pain associated with craniomedial patholog­

ical changes including varying degrees of sub­

scapular tendinopathy, medial glenohumeral

ligament disruption, craniomedial capsular

lesions, and labral tears. The contralateral shoul­

der usually does not show signs of dysfunction,

pain, or spasm on abduction.

A complete work‐up includes history, signal­

ment, gait analysis, orthopedic and neurological

examinations, abduction angle tests, hematology,

biochemical profile, urinalysis, arthrocentesis,

and imaging modalities. Diagnostic musculo­

skeletal ultrasound can identify pathological

changes in the medial compartment such as

(A) (B)

(C) (D)

Figure 12.13 Orthopedic examination for medial shoulder instability. (A) Isolation of the glenohumeral joint with the
examiner’s fingers on the acromial process. (B) With the joint isolated, the glenohumeral joint is then extended. (C)
Abduction of the glenohumeral joint is then performed, while stabilizing the scapula against the body wall. (D)
Goniometry is used to determine the abduction angle.