What causes osteoarthritis?

There are many causes, but practically all can be grouped into two main categories:

1. Abnormal stress on normal joints
   • An injury that damages a joint
   • "Wear and tear": joints are subjected to repeated loads or stress
   • Obesity: an excessive load is put on joints
2. Normal stress on abnormal joints
   • Developmental defects that alter the shape or stability of a joint
   • Poor limb configuration: bow legs or knock knees can cause an uneven load on a joint
   • Genetic predisposition: some breeds of dogs are just more prone to osteoarthritis than others

Hip dysplasia: Normal stresses on a dysplastic (malformed)
joint will lead to arthritis.

Whatever the specific cause, stress on a joint can begin a destructive cycle of inflammation of the joint area and damage to the cartilage that leads to pain for your pet.