Chronic pain in dogs - most commonly from osteoarthritis, cancer, dental disease, and neuropathic conditions - is substantially underdiagnosed and undertreated, representing a major welfare burden. Dogs mask pain behaviours, making owner and veterinary recognition difficult. Validated pain assessment tools include the Helsinki Chronic Pain Index (HCPI), Canine Brief Pain Inventory (CBPI), and observational gait analysis. Research indicates 20-35% of adult dogs have radiographic evidence of osteoarthritis; only 30-40% of these receive treatment. Owner-observed indicators include reluctance to exercise, stiffness after rest, altered posture, and behavioural changes. Treatment options include NSAIDs, monoclonal antibody therapy (frunevetmab/Librela targeting nerve growth factor), physiotherapy, hydrotherapy, and weight management. Emerging research supports multimodal pain management combining pharmacological and non-pharmacological interventions for superior welfare outcomes.