Page 347 - Canine Lameness

19.4 Cranial Cruciate igament Disease 319

(A) (B) (C)

Figure 19.5 A positive “sit-test” is one of the hallmark features indicative of CCLD (A) normal patient
illustrating a “square” sit with both stifles fully flexed; (B) bilaterally positive sit-test showing the limbs
placed on each side of the body; (C) unilaterally positive sit-test indicative of right-sided CCLD.

associated with full flexion of the stifle. This is known as the positive “sit test.” Dogs with unilateral
CCLD may sit with only one stifle extended (and one stifle flexed and positioned normally under
their body); whereas, dogs with bilateral disease may extend both legs. Some dogs will extend both
legs by placing each leg on one side of their body, while others place the less affected limb under STIFLE REGION
their body (Figure 19.5 and Video 19.1). A positive sit test is not pathognomonic for CCLD and may
be observed in novrmal dogs (behavioral), or in dogs with hip or tarsal pathology.

Video 19.1

Positive “sit-test” examples in dogs with CCLD.

Bilaterally affected dogs will shift weight to the thoracic limbs by leaning forward and keeping
the thoracic limbs placed more caudally under the body. These dogs may develop a bodybuilder
appearance with hind end muscle atrophy and thoracic limb muscle hypertrophy. Bilateral dis-
ease severe enough to cause subluxation can result in a dog unable to get up and difficulty ambu -
lating. This may be confused with neurologic disease. Performing a neurologic exam and looking
for proprioception deficits will differentiate neurologic disease from severe bilateral CCLD.

19.4.2.2 Palpation
Degeneration of the CCL typically causes joint effusion, capsular and periarticular thickening, as
well as muscle atrophy. These pathologic changes can be identified on palpation of CCL-deficient
dogs. Standing behind the patient is the best way to detect asymmetries (Video 3.1). The examiner
may appreciate atrophy of the quadriceps, hamstring muscle group, biceps femoris, and cranial
tibialis muscle. In cases of severe stifle joint subluxation, careful palpation of the stifle may show
a cranially displaced tibial tuberosity relative to the patella. Many of the palpable abnormalities
can be identified in the awake patient; however, a sedated physical exam can be very helpful in
testing for joint instability, particularly in large, energetic, tense, or unruly patients. The resulting