Plan 

1) Complete orthopedic exam under general anesthesia
2) Radiographs under general anesthesia with appropriate positioning of joints 
3) Joint tap with collection of joint fluid and serum should be collected for immune test looking for rheumatoid factor.





1) A complete orthopedic exam under general anesthesia would allow for the test for the cranial drawer sign to be completed and determine degree of luxatiion particularly on the left stifle as the dog cried out in pain when the left stifle was manipulated during the physical exam. The complete orthopedic exam should localize the problem areas and give a better indication for what regions  should be focused on and what views (medio-lateral, caudo-cranial, oblique and flexed lateral views) are indicated for radiographs.  A negative cranial drawer sign would likely rule-out a cranial cruciate tear particularly in the left stifle (as the right stifle may no longer demonstrate a positive sign with medial buttressing).
2) Radiographs are indicated for trauma, congenital, and immune-mediated arthritis problems. Radiographs may demonstrate areas of soft tissue swelling indicative of trauma and subsequent inflammation. Bone fractures may appear with signs of remodeling and periosteal bone formation. Stifle joint arthritis (immune-mediated or degenerative joint disease) would demonstrate radiographic signs including periarticular osteophytes, sclerosis and cystic changes in subchondral bone,  and increased joint fluid which is identified by displacement or obliteration of the infrapatellar fat pad on lateral radiographic views. Congenital problems could present with malformations of the femur and/or tibia.
3) A joint tap is indicated for arthritic changes. Although an immune test is low on our priority list for differentials,  it would differentiate immune-mediated arthritis (rheumatoid arthritis) from degenerative joint disease (osteoarthritis).