Effects of analgesia of the discal interphalangeal joint or palmar digitalnerves on lameness caused by solar pain in horses

Objective-To determine if pain of the dorsal margin of the sole in horses c an be attenuated by anesthesia of either the distal interphalangeal (DIP) j oint or the palmar digital (PD) nerves. Study Design-A unilateral forelimb lameness was induced by creating solar p ain. Response to administration of local anesthetic or saline solution into the DTP joint and to administration of local anesthetic around the PD nerv es was evaluated. Animals-Six horses. Methods-Lameness was induced by creating pressure on the dorsal margin of t he sole by screwing set-screws into a nut welded to the inside of each bran ch of a shoe. Gaits were evaluated before and after application of set-scre ws and after a local anesthetic or saline solution was administered into th e DIP joint and, in a second trial, after a local anesthetic was injected a round the PD nerves. Gaits recorded on videotape were evaluated, and lamene ss scores were assigned to each gait. Results-Lameness scores were high after application of set-screws and remai ned high after saline solution was administered into the DTP joint. Scores decreased significantly (P less than or equal to .05) after a local anesthe tic was administered into the DTP joint or around the PD nerves. Conclusions-Analgesia of the DIP joint or the PD nerves desensitizes at lea st a portion of the sole. Clinical Relevance-Pain arising from the sole should not be excluded as a c ause of lameness when lameness is attenuated by analgesia of the DIP joint or PD nerves. (C)Copyright 2000 by The American College of Veterinary Surge ons.