Hip dysplasia is a congenital disease that, in its more severe form, can eventually cause lameness and painful arthritis of the joints. It is caused by a combination of genetic and environmental factors. It can be found in many animals and, rarely, humans, but is common in many dog breeds, particularly the larger breeds.

Luxating patella is a condition where the kneecap (patella) moves out of its normal position. Luxating patella is one of the most common knee joint abnormalities of dogs, but it is only occasionally seen in cats. It may affect one or both of the knees.

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 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 (DJD). It is estimated that 20% of dogs older than one year of age have some form of DJD.