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20.9 ­ctrF Hesrresres ooracHoe ctrf Hip reH o 373

20.8.3 Diagnostics
As mentioned above, muscle palpation is a subjective assessment and therefore confirming a
tentative diagnosis based upon palpation with objective imaging is ideal. Establishing a definitive
diagnosis should include ruling out comorbidities or alternate diseases including lumbosacral
pathology, pathology of the coxofemoral joint, and stifle pathology. Radiographs may show dys-
trophic mineralization or avulsion fractures (Vidoni et al. 2005), but in general they appear normal
(unless comorbidities are detected) and cannot assess muscle fiber pattern for evidence of strain.
Imaging of the iliopsoas muscle typically consists of ultrasonography or MRI. Ultrasonographic
features of the muscle have been described (Cannon and Puchalski 2008) and many dogs that
showed pain upon palpation of the muscle had ultrasonographic changes in one study (Cullen
et al. 2017). Several grading systems (stage/grade I–III with I = mild and III = severe) have
been proposed (Cabon and Bolliger 2013; Cullen et al. 2017). However, these grading systems
have been challenged recently (Mueller-Wohlfahrt et al. 2013).

20.9 Other Diseases Affecting the Hip Region

20.9.1 Sacroiliac Joint
Pain in or around the SI joint is commonly recognized in human medicine secondary to misalign-
ment of the joint, abnormal movement, or insufficient stabilization of the joint. To date, it has
received little attention in veterinary medicine. The SI joint serves to transmit the propulsive forces
from the pelvic limbs to the vertebral column. It also supports the weight of the torso and may help
buffer ground impact forces (Saunders et al. 2013). SI pain is recognized in horses (Jeffcott et al.
1985), but not well documented in dogs. However, given its innervation and similar anatomy, it can
be postulated that disease at the SI joint could cause pain in dogs. A retrospective study evaluating
canine survey radiographs found over 60% of radiographs to have calcification of the interosseous SI
ligaments, and 44% to have calcification of the dorsal and/or ventral SI ligaments (Knaus et al. 2004).
The clinical significance of such radiographic lesions has yet to be correlated with discomfort and HIP REGION
performance issues.
As it is not a well-defined syndrome in dogs, a definitive diagnosis of SI joint pain is difficult to
make. In humans, SI joint disease can cause sciatic pain secondary to compression from piriformis
tension (piriformis syndrome) manifesting as buttock pain, without radiation of pain down the
limb (Foster 2002). In dogs, it has been hypothesized that piriformis tension and muscle spasm
may also occur with SI joint dysfunction and pain (Edge-Hughes 2007). Diagnosis of SI joint dys-
function has been proposed to be based upon movement, and stress testing, as well as evaluation
of anatomic landmarks for asymmetry. Similar methods have been proposed for use in dogs as
well. However, assessing pain of the SI joint specifically in dogs is difficult and subjective and
while any of the below mentioned techniques have been proposed (Edge-Hughes 2007), they have
not been validated and caution must be used when interpreting them.
Yet, evaluating symmetry of the ischial tuberosities, and the iliac crests can be useful. This is
done by standing the dog in a square, equally balanced position, and palpating along the most
caudal portion of the ischial tuberosities for ventral or dorsal rotation of the ilia. The iliac crests
are also palpated for cranial or caudal slip by running the hands along the sides of the back until
the wings of the ilia are found. Additional palpation may include strumming the piriformis
muscle from caudal to cranial while assessing for pain, as well as evaluating the sacrotuberous
ligament for asymmetry of its positioning and for pain on palpation. A pain provocation stress
test based on a human thigh thrust technique has also been proposed: the dog is placed in lateral