Effect of palmar digital perineural analgesia (as a model for "nerving") on forelimb loading over varied surfaces at the walk and trot - a pilot study.

Abstract

BACKGROUND: Navicular syndrome is characterized by palmar foot pain and is a common cause of lameness in horses. Palmar digital neurectomy (nerving) removes sensation to the heel region of the hoof and may serve as a treatment for navicular-afflicted horses, while analgesia (blocking) results in temporary loss of sensation. AIMS/OBJECTIVES: The purpose of this pilot study was to examine the effect of loss of sensation in the heel on the forelimb area and force while tracking on soft and hard ground at the walk and trot. METHODS: Three horses that scored a 0 or 1 on the AAEP lameness scale were fitted to Tekscan hoof sensors via glue-on shoes on the front hooves. Horses completed the same randomized tests of walking and trotting in-hand on hard and soft ground pre and post-nerve blocking. RESULTS: Interaction of ground and blocking status was significant for hoof area (P < 0.0001), with post-blocking having greater loaded area than pre while tracking on hard ground (P = 0.008). The same interaction was found significant for force (P < 0.0001), with tracking over hard ground being greater post-blocking than pre (P = 0.008). Compared to pre-blocking, the heel was more loaded than toe post-blocking for area (P < 0.0001) and force (P<0.001). CONCLUSION: Temporary blocking impacts forelimb loading, and ground type may be an important factor for horses with removed sensation to the forelimb heel. Long-term effects of nerving require further evaluation.