Diagnosis

Canine Hip Dysplasia Ð genetic, heritable malformation of the coxofemoral joint

Pathophysiology --  The dysplastic joint is characterized by varying degrees of 
malformation often including a shallow acetabulum and a deformed, flattened femoral 
head.  The malformation is significant because it inevitably leads to joint laxity or 
instability.  Consequently, the animal is predisposed to subluxation early in life.  This 
malalignment subjects the joint to abnormal forces as the animal moves about.  
Reduction of the weight-bearing contact of the femur and acetabulum concentrates the 
forces over an abnormally small area.  The increased force accelerates articular 
cartilage wear and facilitates degenerative changes in the hip joint.  The joint capsule 
thickens as the body attempts to stabilize the joint.  Osteophytes form during remodeling 
of the femoral head and acetabular rim.  The increased stress necessitates thickening of 
the cancellous trabeculae.  Though such efforts may ultimately stabilize the joint, it is at 
the expense of the articular surfaces.  Chronic inflammation of the soft tissue around the 
joint follows as the animal succumbs to degenerative joint disease.  The inflammation 
results in pain, which causes the lameness.  
	Hip dysplasia is a hereditary disease seen most commonly in large breed dogs 
such as Labrador Retrievers, Rottweilers, German Shepherds, and Golden Retrievers.  
Weight, whether due to large breed or obesity, exacerbates the disease.  Greater activity 
serves to increase stress on the malformed joint.  Additionally, accelerated muscle 
development in large breed puppies facilitated by diet cannot be accommodated by the 
skeletal system.  This can worsen an unstable hip joint.