Autologous mesenchymal stem cells are a proven and easily applicable medicinal product, particularly suitable for the treatment of musculoskeletal diseases (dysplasia, arthritis, tendinopathies) and autoimmune diseases (autoimmune arthritis, idiopathic inflammatory bowel diseases, bronchial asthma) in dogs, cats, and horses. Stem cell therapy is physiological, effective, well-tolerated, and represents a new direction in veterinary medicine.