Canine osteoarthritis (OA) is frequently encountered in dogs. Various methods are available to treat the associated pain, stiffness and lameness. A recently developed method involves the use of nuclear magnetic resonance (NMR), in which a permanent magnetic field is combined with an interfering field. A double-blinded randomized trial was performed to evaluate whether nuclear magnetic resonance treatment (MBST) improved the clinical signs of dogs suffering from osteoarthritis directly and three and six months after treatment. Fifteen dogs received NMR treatment (TG) and 15 received a placebo (PG) over a period of nine days. Symmetry indices of peak vertical force and vertical impulse, lameness and pain score, drop-out, additional pain medication and physical therapy during the course of the study were recorded. An individual score was calculated for each dog to evaluate the overall effectiveness of treatment (OTE) at the three time points. The TG showed significantly improved symmetry indices for vertical impulse and lameness scores at three months after treatment. The findings suggest that NMR had positive effects on the clinical signs of OA in dogs at three months after therapy.