Page 398 - Canine Lameness

370 20 Hip Region

fibrosis affects the more distal myotendinous region and not the origin of the muscle. While the
disease can be unilateral, it often progresses to affect the dog bilaterally.

20.7.1.3 Diagnostics
Definitive diagnosis is made via muscle biopsy; however, the characteristic gait and physical exam
findings generally suffice to make a clinical diagnosis of the disease. Ultrasound may also be used
to confirm muscle pathology. Differential diagnosis for gracilis myopathy includes acute injury to
the gracilis muscle (Section 20.9.3).

20.7.2 Quadriceps Contracture
Quadriceps contracture, sometimes referred to in the literature as tie down, or stiff stifle disease, is
significantly more common than gracilis myopathy. It most commonly occurs following femur
fracture in puppies, or prolonged fixation of the stifle with external coaptation at a young age.
Unlike gracilis contracture, it is a significantly debilitating process as it causes the dog to be unable
to flex the femur or the hock (Bardet 1987).
In addition to contracture occurring following femoral fracture, quadriceps contracture can
occur secondary to parasitic muscle diseases such as Neospora caninum and toxoplasmosis. These
dogs are frequently puppies and are often affected bilaterally. They will initially have weakness and
muscle atrophy in the rear limbs as inflammation secondary to the infection affects the muscles
and nerve roots of the pelvic limb. With progression of the disease they lose their patellar reflex as
lower motor neuron damage progresses, ultimately leading to further muscle atrophy and fibrosis
leading to rigid hyperextension of the pelvic limbs (Crookshanks et al. 2007; Reichel et al. 2007).
Given the two different etiologies and treatment considerations it is important to differentiate
between fracture disease (i.e. quadriceps “tie down” after femur fracture) and parasitic quadriceps
contracture (i.e. due to infectious myositis). Prognosis is considered to be guarded once the disease
HIP REGION disease (Moores and Sutton 2009). Therefore, early treatment with appropriate antibiotics
has advanced; however, successful surgical management has been reported in cases with fracture
(for parasitic quadriceps contracture) and/or rehabilitation is indicated to prevent development of
irreversible changes.

20.7.2.1 Signalment and History
Quadriceps tie down most commonly occurs following femur fracture repair in puppies, but it can
occur in adult animals as well. The risk for development of contracture increases if repair of the
fracture is not appropriate, leading to poor limb use, or if there is a prolonged period of immobili-
zation. Dogs with parasitic quadriceps contracture are also frequently puppies and may have a
history of traveling from or being located in areas exposed to the known pathogens.

20.7.2.2 Physical Exam
On palpation, the quadriceps muscle will feel like a tight band, similar to gracilis contracture. With
fracture disease, there are adhesions between the muscle and femur as well as periarticular fibrosis.
Dogs may initially only show atrophy of the quadriceps with poor limb use. As the muscle fibrosis
progresses, function will decrease significantly, and the dog will have difficulty ambulating. In
severe cases, since dogs cannot flex their stifle or hock, they will walk with a straight limb, often
scraping the dorsum of the foot leading to open wounds (Figure 20.14). The stifle and tarsocrural
joints are unable to be flexed, even under heavy sedation. There may be pain associated with
palpation of the muscle belly. In extreme cases, there may be genu recurvatum (i.e. stifle bent