Stem cells are unspecialized cells that are capable of renewing themselves though cell division. Under certain conditions, they can become a specific tissue or organ cell. Stem cell therapy commonly refers to the process of placing stem cells from the body into diseased or damaged tissues, such as a torn ligament in the knee or perhaps an arthritic joint. This process is often referred to as regenerative medicine. Adult stem cells are capable of repair and regeneration of various tissues because they have the potential to differentiate into specialized cells of an organ. The most common use of stem cell therapies has been in the treatment of osteoarthritis in dogs and cats. Currently, there are no current guidelines with respect to stem cell therapy. Stem therapy should only be performed by a veterinarian with special training, who understands the benefits and limits of this therapy. It is important to have realistic expectations as positive outcomes cannot be guaranteed.