Effects of magnesium with or without boron on headshaking behavior in horses with trigeminal‐mediated headshaking

Abstract Background Oral administration of magnesium and boron might have a beneficial effect on headshaking behavior in horses. Objective Evaluate the effects of oral magnesium alone or in combination with boron on headshaking behavior in affected horses. Animals Twelve geldings (6 healthy controls and 6 affected). Methods Prospective randomized controlled dietary trial over 42 days in 12 horses (6 horses diagnosed with trigeminal‐mediated headshaking and 6 unaffected healthy controls). All horses received a hay diet and were randomized into 3 treatment groups: pelleted feed combination (PF), pelleted feed combination with magnesium (M), and pelleted feed combination with magnesium‐boron (MB) with a week washout of hay only between treatments. Headshaking behavior and biochemical blood variables were assessed at baseline (hay only) and then after each week of supplementation. Results All 3 diet interventions increased blood ionized and total magnesium. Groups M and MB further increased Mg2+ when compared to PF. Horses receiving treatments had a significant reduction in headshaking behavior, as measured by incidence rate ratio (IRR), when compared to unsupplemented hay diet (44% for PF, IRR, 0.558; CI, 0.44, 0.72; P < .001; 52% for M, IRR, 0.476; CI, 0.37, 0.62; P < .001; and 64% for MB, IRR, 0.358; CI, 0.27, 0.48; P < .001). Conclusions and Clinical Importance Magnesium in combination with boron had the greatest decrease in headshaking. Oral supplementation with magnesium or magnesium in combination with boron should be considered in horses affected with headshaking