Dog harnesses are a popular walking aid used on pet dogs. Research has focused on the biomechanical impact of assistance dog harnesses, however, is lacking in the pet dogharness industry. This study aimed to explore the impact of six different harness types oncanine biomechanics compared to a standard (base) collar, specifically shoulder extension,shoulder flexion, elbow extension and elbow flexion. A high-speed recording device recordeda total of twenty-one videos per dog (n=30), and analysis demonstrated that the straight-front harness allowed for the most elbow and shoulder extension and flexion, whereas thefront-clip allowed for the least, therefore causing the largest reduction of biomechanics. Bydirectly comparing the six harnesses, three of which are new to research inclusion, theevidence drawn demonstrates which harnesses should be utilised more, and which shouldpotentially be avoided. These results provide the starting point for future study, andrecommendations have been outlined, specifically considering breed difference,morphological impacts, and long-term effects of harness design on canine gait. Withadvancements in the canine industry, this research is indispensable to maximise safety andpotentially prevent or delay various musculoskeletal disorders.