The most common type of arthritis is osteoarthritis which can be due to wear and tear on joints from over use, aging, injury, or from an unstable joint such as which occurs with a ruptured ACL (anterior cruciate ligament) in the knee. The chronic form of this disease is called degenerative joint disease

The rupture of the cruciate ligament is the most common knee injury in the dog. This injury has two common presentations. One is the young athletic dog playing roughly who acutely ruptures the ligament and is non-weight bearing on the affected hind leg. The second presentation is the older, overweight