Diagnostic nerve blocks used during lameness examinations don’t adversely affect how horses move after the lower limbs are numb.

An experimental study looked for changes in the center of pressure (COP) path during the stance phase before and after nerve blocks of normal horses without signs of lameness. Pressure-sensitive foils were taped to the hooves, and the horses were trotted in hand before and after the diagnostic nerve blocks were applied at the level of the proximal sesamoid bones to numb the lower limb.

As expected, the COP paths were different for each horse and each limb; however, within each horse, there was little variation between strides. This pattern was unchanged with no increase in the variability of the COP path after the nerve blocks. The location of initial contact, COP during mid-stance and point of breakover were not affected by unilateral or bilateral diagnostic nerve blocks of the foot.

These results suggest that when changes in the COP path, breakover, etc., are noticed after a diagnostic nerve block, this should be interpreted as clinically relevant (i.e. related to a cause of lameness in that area) and investigated further, such as with diagnostic imaging.

— Hagen J et al. JEVS 2021;in press