Plan of Action

The individual stifles should be manually restrained in a flexed position and subsequently 
the dog should be walked (flexion test) to see if the lameness in the right or left stifle is 
more pronounced.  The animal should also be walked in a circular pattern to place more 
pressure on the inside limb. This should accentuate any lameness on the inside leg.  Palpate 
the entire limb with particular attention placed on the joints for signs of inflammation such 
as swelling and heat.  

The patient must be sedated so that cranial drawer can be attempted on the left limb and 
repeated on the right.  Partial rupture will reveal increased cranial drawer in the flexed 
position, minimal movement in the 140 position, and no cranial drawer on extension.  
Palpate for crepitence, clicking, popping, or Ògiving wayÓ as evidence of meniscal injury, 
which often accompanies CCL. Extend both rear limbs to compare their symmetry and 
length.  

Radiographs of both stifles should be taken while the patient is sedated.  The patella may be 
in or out of the trochlear groove, depending upon whether or not itÕs fixed medially.  A 
skyline view can assist in determining the size, shape, and depth of the trochlear groove.  
In chronic medial patellar luxation, we expect to find a shallow groove and small medial 
trochlea.  We want to watch for femoral and tibial bowing, tibial crest rotation, and 
secondary degenerative joint disease.  If cranial cruciate ligament rupture is involved, the 
actual rupture is not visible on radiographs, but radiographs should reveal the cranial 
drawer sign and displacement of the infrapatellar fat pad by edema or joint effusion.	
Radiographs could also determine if the lameness is due to a form of arthritis.  With 
osteoarthritis, the radiographs would show a narrowed joint space, periarticular osteophyte 
formation and sclerotic changes of the subchondral bone in more severe cases.  
 
If there are no signs of radiographic changes, then systemic lupus erythematosus should be 
considered since the patient is exhibiting lameness with periodic dermatological signs.  An 
anti-nuclear antibody (ANA) test and CBC should be performed.  A positive ANA test is 
indicative, with the clinical signs, for lupus.