Plan of Action
     To make a definitive diagnosis we will perform radiographs of both the 
right and the left stifle joints.  Radiographs will be taken under mild sedation 
using a sedative/muscle relaxant type drug such as Valium.  In addition to the 
standard mediolateral and caudocranial views of the stifle joint, the use of 
oblique and flexed lateral views will be applied to detect degenerative changes.  
While we have the patient sedated we will perform an orthopedic exam.  We will 
evaluate both the right and left stifle joints for laxity (cranial drawer, 
caudal drawer, medial buttressing, lateral buttressing, tibial rotation).  We 
will aspirate stifle joints to collect synovial fluid for analysis.  We will 
perform a CBC to check for inflammation/infection.  We will also analyze total 
protein and globulin levels and test for the presence of autoagglutination.  If 
the client approves and afford the cost we would like to perform an MRI to 
detect defects in articular cartilages and increased signal intensity from the 
meniscus of the stifle joints.    


Changes expected:
Hypothesis 1--Immune-mediated/Infectious
Radiographs of stifles should reveal joint erosion and degeneration.  The joint 
erosion and degeneration would appear as described below in Hypothesis 2 and 3.  
If it is a non-septic arthritis we would expect to find the following in the 
joint synovial fluid:  slight turbidity, yellow or pink color, decreased 
viscosity, increased nucleated cell count, presence of antibody-antigen 
complexes and a bacteria negative culture.  If it is septic arthritis we would 
expect to have a positive bacterial culture from the synovial fluid.   

Hypothesis 2—Trauma
Radiographs of stifles should reveal increased joint fluid with displacement of 
the infrapatellar fat pad.  Periarticular osteophytes may also be seen on the 
medial and lateral femoral trochlear ridges, the distal border of the patella, 
the proximal border of the patella, and proximal tibia.  Other changes seen may 
include subchondral bone sclerosis, narrowing of the medial and/or lateral joint 
space, flattening of articular surfaces and varus or valgus deformity.  We 
wouldn't expect to culture any bacteria from the stifle joint synovium nor would 
we expect to find antibody-antigen complexes present.  Due to inflammation in 
the joint we may see increased synovial cell counts.       

Hypothesis 3--Degenerative Changes
Radiographs of stifles should reveal increased joint fluid with displacement of 
the infrapatellar fat pad.  Periarticular osteophytes may also be seen on the 
medial and lateral femoral trochlear ridges, the distal border of the patella, 
the proximal border of the patella, and proximal tibia.  Other changes seen may 
include subchondral bone sclerosis, narrowing of the medial and/or lateral joint 
space, flattening of articular surfaces and varus or valgus deformity.  Due to 
inflammation in the joint we may see increased synovial cell counts.