Field trials unbacked by clinical trails suggest that magnetic fields influence wound healing, the reduction of posttraumatic oedema, improvement in the function of arthritic joints, reduction of the pain associated with thoraco-lumbar problems, tendon injuries, fractures and other bone-assisted conditions.
While all manu- facturers lay down specific treatment instructions, a minimum of three weeks' treatment is suggested even if clinical signs have disappeared. This is because working on the hypothesis that magnetic field has triggered cell activity by external stimuli and that the activity is not just the body's own reactive control, by the end of a 21-day period some form of effective healing should have occurred. Field work suggests that cessation of treatment with cessation of pain (often the only objective finding), which may occur early in the treatment programmed, may lead to recurrence of symptoms -- in many cases with increased severity.
Equine Injury, Therapy and Rehabilitation, Second Edition. Mary Bromiley, page 81, 82. Publishers, Blackwell Science, copyright 1983, 1993.