A Protocol for Prolonged Surgical Anaesthesia with Recovery in Fire Salamanders Using Tricaine Mesylate (MS-222): A Case Series

Abstract

The objective of this study was to describe prolonged surgical anaesthesia and recovery in fire salamanders ( Salamandra salamandra) using tricaine methanesulfonate (MS-222). A total of 14 salamanders were anaesthetised for electromyography wire implantation. Sodium bicarbonate buffered solutions (0.5–4 g l–1) of MS-222 were prepared (adjusted to pH 7.0). Anaesthesia was induced by partial immersion in pre-oxygenated 3 g l–1 solution for 20 min. Buprenorphine (0.5 mg kg–1) was administered subcutaneously. During microsurgery, heart rate (HR), solution pH and temperature were recorded. Reflectance pulse oximeter (SpO2) (Masimo Rad-57) was recorded in two salamanders. Anaesthetic plane and MS-222 pH stability (pH 7.6) were maintained by renewing administration of oxygenated MS-222 solution (0.5–3 g l–1) onto swabs that partially covered the body. Recovery started at the end of surgery (MS-222 0 g l–1). Postoperatively, salamanders were given oral meloxicam (0.2 mg kg–1). Mean time for loss of righting reflex during induction was 13.7 ± 2.2 min. Duration of anaesthesia and time to recovery were 111 ± 24.2 and 31 ± 10.3 min, respectively. Due to complications, two salamanders did not recover. Baseline HR was 67.4 ± 34.5 beats/min, and it decreased significantly until recovery ( p ≤ 0.0001). In two salamanders, baseline SpO2 was 85.5% ± 14.5, SpO2 during surgery was 61% ± 6.4, improving to 80.5% ± 2.1 on recovery. In conclusion, prolonged recovery anaesthesia is achievable with MS-222 dilutions in salamander. Reflectance SpO2 could prove valuable during immersion anaesthesia.