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15.5 Traumatic Shoulder Luuation 235

is more difficult to assess, particularly in overweight dogs. In one study, poor correlation between
ultrasonographic and arthroscopic evaluation of the SST was described (Cogar et al. 2008). To facil-
itate evaluation of the MGL and SST, sedation and a hockey-stick probe are recommended (Cook
2016). Benefits of ultrasound include the relatively low cost, ability to perform the examination
without general anesthesia, and possibility of performing a dynamic assessment. However, inter-
pretation of the images can be challenging and requires advanced training. If both, MRI and ultra-
sound are performed, MRI should ideally be done prior to ultrasound to avoid creation of
artifacts.
Shoulder arthroscopy has been recommended as the gold standard for diagnosing MSI (Devitt
et al. 2007). Arthroscopy allows excellent assessment of the intra-articular shoulder structures,
including the intra-articular components of the MGL and the SST. These structures can also be
placed under stress by abduction of the shoulder during arthroscopy or palpated with a probe.
Arthroscopy can also help identify concurrent shoulder pathologies, for example changes to the
biceps tendon that may occur secondary to the inflammation associated with MSI. Such changes
(secondary biceps tendinopathy) must be differentiated from primary biceps tendon disease as this
may influence the treatment. Standard arthroscopy allows to establish a diagnosis and proceed
with potential treatment at the same time, if indicated. The disadvantage of arthroscopy is that the
evaluation is limited to the intra-articular structures.
Since treatment for MSI is frequently nonsurgical, needle arthroscopy may also be used if the
focus is on the diagnostic aspect. This technique was initially reported as a diagnostic tool in horses
and uses a smaller arthroscope that can be used under sedation (Frisbie et al. 2014). Needle arthros-
copy has recently been assessed for diagnostic exploration in dogs (Fournet et al. 2018) and is
becoming more commonly used in small animal practice. The author uses needle arthroscopy if
advanced imaging has not revealed a diagnosis and if it is not clear that standard arthroscopy is
indicated. The current technical difficulty associated with needle arthroscopy is obtaining high-
resolution images similar to those acquired when using standard arthroscopy.
While CT (and CT arthrography) is a convenient and more readily available imaging modality, it
is of limited use for the diagnosis of MSI (Eivers et al. 2018). However, CT is useful in ruling out
other diseases (such as shoulder osteochondrosis dissecans [OCD] and elbow dysplasia). A recent
report suggested that adding epinephrine to the contrast medium may improve image sharpness SHOULDER REGION
by delaying diffusion of the contrast (De Simone et al. 2013). Similarly, while joint fluid analysis
can be helpful for other joints, dogs with significant pathology may show no cytological abnormali-
ties in their joint fluid (Akerblom and Sjostrom 2007).

15.5 Traumatic Shoulder Luxation

Shoulder luxation (Figure 15.9) is an uncommon condition that is typically a consequence of trau-
matic injury in dogs. This condition is different than the above-described low-grade, chronic insta-
bility of the shoulder joint (MSI). Luxation direction (based on the location of the humerus) is
most commonly medial, although lateral, cranial, and caudal have all been reported. Congenital
deformities (Section 15.10.2) may also result in luxation, which tend to be medially displaced.
These must be differentiated from traumatic luxations since the treatment is different (i.e. closed
reduction is not indicated). Acute, traumatic luxations can often be managed with closed (manual)
reduction followed by external coaptation (e.g. Velpeau sling for medial luxation; spica splint for
all others). If the joint is grossly unstable even after reduction, or medical management fails, surgi-
cal stabilization is recommended.