Effects of Bupivacaine Infiltration Anesthesia Using Temperature-Responsive Hydrogel in Dogs Undergoing Celiotomy

The multimodal analgesic strategy involving local anesthesia at the incision site is effective for postoperative pain relief in dogs undergoing celiotomy.Numerous studies have been conducted on drug delivery systems, such as ez:AP (TGel Bio, Co., Ltd., Republic of Korea), a temperature-responsive hydrogel (TRH).TRH exhibits unique properties, including transitioning from a liquid state at 2-8C to a gel state at above 30C.This study aimed to investigate whether combining TRH with bupivacaine, a commonly used local anesthetic, could prolong the analgesic effect in dogs undergoing celiotomy compared with administering bupivacaine alone.Eleven dogs that underwent celiotomy were included in this study.Bupivacaine alone or combined with TRH was used for local infiltration anesthesia.Subsequent pain assessment was conducted at 2-h intervals during the next 24 h using the short form of the Glasgow composite measure pain scale.The results showed that the sensory recovery commenced 16-22 h after a single administration of TRH combined with bupivacaine for infiltration anesthesia, with the analgesic effect lasting for more than 24 h.In the case of bupivacaine alone, both sensory recovery and the duration of the analgesic effect commenced and lasted for about 6-8 h.This study revealed that the use of bupivacaine combined with TRH for local infiltration anesthesia during celiotomy can extend the duration of local analgesic effects, thus providing substantial benefits in postoperative pain management.