Front Matter

Chapter 14 Disorders of the Pelvic Limb: Diagnosis and Treatment 359

exercises. Weekly to biweekly rehabilitation and
reassessment allows adaptation of the therapeu­
tic exercise plan and home care. Complementary
therapies such as acupuncture and chiropractic
are also often used to promote whole‐patient
wellness.
For muscle strains in which core lesions are
noted, or those refractory to rehabilitation, ultra­
sound‐guided injection with orthobiologics
may be performed (see Chapter 16).
Surgical treatment by tenotomy may be
warranted when there are irreversible changes
to the myotendinous unit that are nonrespon­
sive to medical management and rehabilitation
therapy.

Gracilis and semitendinosus/
semimembranosus myopathy

Myopathy of the gracilis, semitendinosus, or
semimembranosus muscles may occur individu­
ally, or concurrently. There is usually no defini­
tive episode reported by the client. There does
appear to be some breed and age predilection,
with highly active German Shepherd Dogs and
Shepherd‐related breeds between the ages of 3
and 7 years overrepresented (Vaughan, 1979;
Lewis et al., 1997; Steiss, 2002).

Anatomy

The gracilis, semitendinosus, and semimem­
branosus muscles form an extensive broad
muscular sheet that is found superficially in the
caudal portion of the medial thigh (Figure 14.7).
The semitendinosus muscle arises from the
ischiatic tuberosity and ends along the cranial
border of the tibia. An aponeurosis also spreads
out into the crural fascia and from its caudal
border sends a well‐developed reinforcing
band to the calcanean tendon, which attaches to
the tuber calcaneus. This muscle group is
responsible for thigh adduction, hip extension,
stifle flexion, and tarsal extension (Evans, 1993).

Pathophysiology

In most cases, the etiology of gracilis/semitendi­
nosus myopathy is unknown. Numerous theories

exist, including acute trauma, chronic repetitive

trauma, autoimmune disease, drug reaction,

infection, neurogenic disorders, and vascular

abnormalities (Taylor & Tangner, 2007). Ischemia

secondary to indirect trauma may also lead

to  fibrosis and contracture (Taylor & Tangner,

2007). Histologically, muscle is replaced by

dense, collagenous connective tissue.

A 2002 study involving canine athletes sug­

gested that excessive activity can lead to muscle

strains resulting in inflammation, edema,

localized hemorrhage, and eventually fibrosis

(Steiss, 2002). German Shepherd Dogs may be

at greater risk of muscle strain during physical

activity due to the increased angulation (flexion)

at the stifle (Steiss, 2002).

Diagnosis

Presentation of gracilis, semitendinosus, or

semimembranosus contracture is very unique

and consistent in appearance. The diagnosis can

be made with a thorough history, observation

Pectineus

muscle

Sartorius

Adductor muscle

muscle

Semimembranosus

muscle

Semitendinosus

muscle

Gracilis muscle

Figure 14.7 The gracilis, and lateral to that muscle, the

semitendinosus and semimembranosus muscles, form

an extensive broad muscular sheet that is found

superficially in the caudal portion of the medial thigh.

Source: Illustration by Marcia Schlehr.