Development and Clinical Application of Pudendal Nerve Block Using a Peripheral Nerve Locator for Reproductive Surgery in Horses

Aims: To develop, describe and evaluate clinical applicability of pudendal nerve block using a peripheral nerve locator. 

Methods: In a pilot study, 6 ponies were used to determine the correlation between nerves serving the perineal region (namely pudendal, caudorectal and perineal nerves) and the muscle contractions observed when an electrolocation technique was used. After appropriate electrolocation a small volume of lidocaine/methylene blue solution was injected under general anaesthesia. The dye location relative to the specified nerves was examined after humane euthanasia followed by dissection of the relevant region. In a second experiment, 7 Thoroughbred horses were used to evaluate the appropriate volume of lidocaine solution for the nerve block. Lidocaine/methylene blue solution was injected after positive electrolocation immediately (5–40 min) after euthanasia. A stained segment of 2 cm or more of the nerve was deemed to be sufficient and was evaluated after dissection. Finally, evaluation of a bilateral pudendal nerve block was used to provide anaesthesia and analgesia in 10 clinical cases involving both mares and geldings. [...]