Hypothesis One: Degenerative Changes in theJoint

	Clinical signs of pain in the joints, a limited range of motion, and lameness 
signify a degeneration of the coxo-femoral joint.  Joint degeneration occurs when 
cartilage is broken down.  When the catabolic processes of the joint such as collagenase 
and metalloproteinases and stromelysin, exceed the anabolic processes of the joint, 
cartilage is destroyed.  With the loss of cartilage, the architecture of the joint is changed.  
The Ortalani sign for joint laxity demonstrates this.  The subchondral bone thickens 
leading to a decrease in compliance of tissue.  As a result the adjacent bone surfaces 
come into more contact with each other, increasing friction.  This explains why we saw a 
reluctance to climb stairs, discomfort while sitting, pain upon extension of the left hip, 
and pain increased with exercise or immobility.  The change in joint architecture would 
also lead to lameness and a deviation in how the dog carried her weight. We believe this 
disease is in the early stages as the dog is only nine months old, the lameness is only a 
grade 1 out of 4 and there is no evidence of muscle pain or atrophy.  This animal could 
have been predisposed to this degeneration due to a congenital defect.