Short term use of balance pads on postural sway and musculus multifidus cross sectional area in horses

Horses with musculoskeletal injuries have poor postural stability with larger center of mass (COM) movements and asymmetry/atrophy of the musculus (m.) multifidus. The objective of this study was to determine the effect of balance pad use in horses on both COM motions and m. multifidus cross sectional area (CSA). We hypothesized that use of balance pads would decrease COM motions and increase m. multifidus CSA and symmetry. Six healthy adult horses stood on balance pads for 5 min twice daily, 5 days per week for 4 weeks. At baseline and study completion, COM motion was determined using a portable media device, with horse standing on and off balance pads. Ultrasound of m. multifidus was performed bilaterally at select thoracic (T) and lumbar (L) vertebra: T12, T14, T16, T18, L2, and L5. Data were analyzed using mixed-model ANOVA. At baseline, there was significantly more medial-lateral and cranio-caudal motion when horses stood on pads compared to square stance (P < 0.006). When standing on pads, there was a significant decrease in motion at 4 weeks compared to baseline (P < 0.0004). There was a significant increase in m. multifidus CSA at T14 at 4 weeks compared to baseline (P = 0.021). When comparing baseline and 4 weeks CSA, there was no significant difference in m. multifidus asymmetry. These results suggest that implementation of balance pads for 4 weeks can improve postural stability in horses and increase CSA at T14. Longer duration of use may be needed for additional changes to paraspinal musculature.