Use of total intravenous anesthesia with propofol and a vaporizer-free ventilator to prevent recurrence of malignant hyperthermia in a dog.

Abstract

Malignant hyperthermia (MH) is a rare, life-threatening perioperative complication most commonly triggered by inhalant anesthetics or depolarizing neuromuscular blocking agents. Genetic variants affecting skeletal muscle are believed to underlie the susceptibility to MH. Although total intravenous anesthesia (TIVA) has been employed in human patients with MH susceptibility as a nontriggering alternative, comparable data and standardized protocols are limited in veterinary medicine. A 13-year-old spayed female Toy Poodle dog with a history of suspected MH during isoflurane anesthesia 4 years earlier, characterized by a rapid increase in body temperature (42.0 °C) and end-tidal carbon dioxide tension (PE´CO), and successfully treated with active cooling and dantrolene administration, presented for treatment of an asymptomatic tongue mass. General anesthesia was planned to facilitate a thorough oral examination and biopsy. TIVA with propofol was performed to prevent MH recurrence, using a vaporizer-free ventilator. Following anesthetic premedication with buprenorphine (20 μg kg, intravenously) and atropine sulfate (25 μg kg, subcutaneously), anesthesia was induced with propofol to allow endotracheal intubation and maintained with a propofol variable rate intravenous infusion (0.4-0.5 mg kgminute) under mechanical ventilation with 100% oxygen. Dantrolene was available but was not required. During the 37-minute anesthetic period, rectal temperature gradually decreased, and PE´COremained stable. Inspired isoflurane fraction was undetectable during the perioperative period. Recovery was smooth, and postoperative blood tests revealed only mild creatine kinase elevation. Whole-genome sequencing of peripheral blood DNA revealed a missense variant in the ryanodine receptor gene (RYR1), identical to a known human MH-causing mutation (p.Arg2435His). This case suggests that propofol-based TIVA combined with a vaporizer-free ventilator can safely prevent MH recurrence in genetically susceptible dogs, highlighting the importance of eliminating all potential MH triggers in susceptible individuals.