508 Canine Sports Medicine and Rehabilitation
within the tendon. More commonly, supraspi-
natus tendon changes are chronic in nature.
The echogenicity is also mixed, but the changes
will be hyperechoic, indicative of dense fibrous
(scar) tissue or potentially dystrophic minerali-
zation. Mineralization is differentiated from
fibrous tissue by acoustic shadowing below the
lesion (Figure 20.7).
In general, the normal biceps tendon has an
increased echogenicity in cross‐section and
sagittal views compared with the supraspina-
tus tendon. Biceps tendon abnormalities
noted on ultrasound include changes in size
and shape, bony reaction along the supragle-
noid tubercle due to tearing of fibers from the
origin, irregular margins, increased fluid
around the biceps tendon, and hypoechoic
lesions within the tendon itself. In the cranio-
lateral shoulder, the infraspinatus and teres
minor tendons can also be evaluated. Medial
shoulder structures are also frequently impli-
cated in shoulder joint lameness, but are dif-
ficult to visualize reliably with ultrasound
and require special probes and heavy seda-
tion (Cook, 2016).
Pelvic limb ultrasonographyUltrasound evaluation may also prove useful
in diagnosis of lesions involving the iliopsoas,
stifle, and tarsus.Iliopsoas
The iliopsoas, from the origin of the psoas
major muscle on the cranial lumbar vertebrae
to the musculotendinous junction and the ten-
dinous insertion on the lesser trochanter, is sub-
ject to both acute and chronic injury. Evaluation
of the normal ultrasonographic anatomy has
been described (Kramer et al., 1997). Lesions in
the muscle belly of the psoas major will have
the appearance of either acute or chronic change
and may include, depending on severity: irreg-
ular boundaries between muscles, increased
echodensity indicative of cellular infiltrate, dis-
ruption of normal muscle striations, changes
in size/thickness, or hypoechoic or anechoic
areas within the muscle (Breur & Blevins, 1997).
Disruption of the normal linear arrangement of
the tendon fibers, changes in echogenicity, and
thickening of the tendon are commonly encoun-
tered in chronic injuries (Breur & Blevins, 1997;
Nielsen & Pluhar, 2005; Cook, 2016).Stifle
Evaluation of the stifle using ultrasound has
mixed results. In two studies looking at the value
of ultrasonography to assess for cranial cruciate
ligament rupture, it was positively identified in
only 19.6% and 15.4% of dogs examined who
were definitively diagnosed with rupture at sur-
gery (Gnudi & Bertoni, 2001; Arnault et al., 2009).
This low sensitivity is not surprising when
understanding the anatomic location of the cru-
ciate ligament as well as the physics of ultra-
sonography. Bone fragments and osteochondral
lesions are also difficult to evaluate for similar
reasons. For example, evaluation for fragmented
medial coronoid process has been shown to be
unreliable due to the anatomic location of the
fragments and joint size (Cogar et al., 2008; Cook
& Cook, 2009). Evaluation of the meniscus with
ultrasound has good sensitivity and specificity
for the identification of meniscal injury and may
be an important application in evaluation of the
stifle joint prior to surgery for cranial cruciate
ligament rupture (Kramer et al., 2001; Piórek &Figure 20.7 Ultrasonographic image of the infraspinatus
tendon that has significant disruption and mineralization
(blue arrows). Mineralization is hyperechoic with
acoustic shadowing present deep to the mineralization
(green arrow).