Page 261 - Canine Lameness

15.4 Medial Shoulder nstaaility 233

(A) (B)

(C)

Figure 15.7 Shoulder abduction test: (A) subjective evaluation of the degree of shoulder abduction during
stance which also allows to evaluate for a pain response; (B) goniometric evaluation in lateral
recumbency – for the measurements to be accurate, the elbow and shoulder must be fully extended; the
center of the goniometer is placed over the shoulder joint, the two limbs of the goniometer are aligned
with the spine of the scapula and the humerus; (C) note, if the elbow is not fully extended as illustrated in SHOULDER REGION
the image, an (false) increased goniometric measurement may result.

crepancy may be due to breed variability and function, or inclusion of dogs that were affected by
nonclinical MSI, or discrepancy of measurement techniques. An increased abduction angle makes
a diagnosis of MSI more likely (Devitt et al. 2007); however, a “normal” shoulder abduction angle
does not rule out MSI. Like cranial cruciate ligament disease, partial tearing of the MGL and SST
may not result in detectable instability. Although in the authors’ experience, these patients
frequently show a more pronounced pain response during abduction.
Because of the subjective nature and variability associated with the shoulder abduction test, it
should only be used as a guide in making a diagnosis of MSI and considered in combination with
other diagnostics. In unilaterally affected dogs, abduction angles should be evaluated by compar-
ing the affected and non-affected side. A diagnosis of MSI is more likely if a patient has signifi-
cantly higher abduction on the side the patient is lame compared to the non-lame side.
Despite these possible limitations of goniometric assessment of abduction angles to help diag-
nose MSI, it remains the mainstay of diagnosis since definitive tests are more costly and involved.
The authors therefore recommend applying this test to any dog presenting with thoracic limb
lameness, keeping its limitations in mind.