Hypothesis 3: Damage to the stifle joint.


	Trauma can cause damage to the stifle joint.	 The most likely injury that would occur in the stifle is the rupture of the cranial cruciate ligament.  This would cause an acute onset of non-weight bearing in the affected limb, which has occurred.  Capsular distention should also be felt, but palpation is unable to be performed in this dog due to the tremendous swelling.  A positive cranial cruciate drawer is also expected.  If the injury is not a complete tear of the cranial cruciate ligament, but rather a partial tear, some differences are expected.  We would expect to see increased cranial drawer in the flexed position and no cranial drawer in the extended position.  Depending on the severity of the tear, we would expect to see some to minimal movement in the 140 degree position.  Radiographs may indicate subcapsular swelling.  Current radiographs should not show signs of osteoarthritis as bone remodeling is a chronic process and not enough time has elapsed to allow this to occur.  Other chronic signs that should not be felt in this case are medial buttressing or meniscal injury.