Arthritis involves the breakdown of cartilage. Cartilage normally protects the joint, allowing for smooth movement. Cartilage also absorbs shock when pressure is placed on the joint, like when your dog is walking or running. Without the usual amount of cartilage, the bones rub together, causing pain, swelling (inflammation), and stiffness.

An animal may have joint inflammation for a variety of reasons, including:

• An autoimmune disease (the body attacks itself because the immune system believes a body part is foreign)
• Broken bone
• General "wear and tear" on joints
• Infection (usually caused by bacteria or viruses)

Often, the inflammation goes away after the injury has healed, the disease is treated, or the infection has been cleared.

With some injuries and diseases, the inflammation does not go away or destruction results in long-term pain and deformity. When this happens, you have chronic arthritis. Osteoarthritis is the most common type and is more likely to occur as dogs age. They may feel it in any of their joints, but most commonly in their hips, knees or paws. Risk factors for osteoarthritis include:

• Being overweight
• Previously injuring the affected joint
• Using the affected joint in a repetitive action that puts stress on the joint

Petgensys scientists regularly update this list to reflect the most current published and unpublished research.

• Osteoarthritis, angiogenesis and inflammation
• Molecular basis of osteoarthritis: biomechanical aspects