Effect of a static magnetic field on blood flow to the metacarpus in horses.

OBJECTIVE To determine the effect of a static magnetic field on relative blood flow to the metacarpus of horses. DESIGN Randomized controlled clinical trial. ANIMALS 6 healthy adult horses. PROCEDURE Red blood cells were radiolabeled in vivo by administration of technetium Tc 99m (pyro- and trimeta-) phosphates, and scintigraphic images were obtained 30 minutes later. A magnetic wrap that emitted a static magnetic field was applied to 1 metacarpus and a control wrap was applied to the contralateral metacarpus. Forty-eight hours later, the wraps were removed, and scintigraphy was repeated. Relative perfusion ratios were calculated by dividing mean count per pixel for the portion of the metacarpus under the wrap by mean count per pixel for a portion of the distal aspect of the antebrachium that was not in the magnetic field. RESULTS The difference between the relative perfusion ratio prior to application of the wrap and the ratio after application of the wrap for limbs that received the magnetic wrap was not significantly different from the difference in ratio for limbs that received the control wrap. CONCLUSIONS AND CLINICAL RELEVANCE Results suggest that in horses, the static magnetic field associated with application of commercially available magnetic wraps for 48 hours does not increase blood flow to the portion of the metacarpus underneath the wrap.