Osteoarthritis (OA) is a chronic inflammatory degenerative joint disease that affects humans and animals alike. Currently, >20% of the adult and 80% of the geriatric dog population in the US (>90 million) suffer from OA. The pathophysiology of OA is very complex as it involves multiple mechanisms and molecular pathways. Currently, there are several choices to manage OA, but many veterinarians choose nutraceuticals because of lesser or no side effects compared to pharmaceuticals. The present investigation was undertaken to assess anti-arthritic efficacy and safety of Flex Choice TM chews (Clinics Choice, LLC) in dogs with moderate OA. Flex Choice TM chews are composed of krill oil, hyaluronic acid, astaxanthin, Boswellia serrata extract, greenlipped mussel, and iron transport tocopheryl polyethylene glycol succinate (ITPGS). Dogs with OA received Flex Choice TM chews b.i.d. for 150 days. Each month, dogs were given a full exam and were evaluated for arthritic pain (overall pain, pain upon limb manipulation, and pain after physical exertion) using the Glasgow scoring system, CBC, and serum biomarkers of liver (bilirubin, ALT, and AST), kidney (BUN and creatinine), and heart and skeletal muscle (CK) functions. Dogs receiving Flex Choice TM showed marked reductions in overall pain (52%), pain upon limb manipulation (35%), and pain after physical exertion (40%). The active ingredients in Flex Choice TM exert antioxidative, anti-inflammatory, immunomodulatory, analgesic, cartilage repair and anti-osteoarthritic effects. ITPGS, in addition to being a bioenhancer, exerts its effects such as antioxidative and anti-inflammatory. No significant (P>0.01) change occurred in physical parameters, CBC, and serum biomarkers of liver, kidney, and heart functions. Findings revealed that Flex Choice TM significantly ameliorated OA-associated pain, and it was well tolerated by dogs with moderate OA.