Malignant hyperthermia in dogs during general anaesthesia

Malignant hyperthermia is a pharmacogenetic disorder of skeletal muscles developing as a hypermetabolic response to inhalation anaesthetics such as halothane, sevoflurane or isoflurane and depolarizing muscle relaxants such as succinylcholine. It is produced by mutation of the RYR1 gene in dogs. In anaesthetised dogs, regardless of the anaesthetic drugs used, calcium ion channel activity may change and malignant hyperthermia may develop. Clinical features are hyperthermia, tachypne, hypercarbia, increased oxygen consumption, severe metabolic acidosis, hyperkalemia, cardiac arrhytmias and muscle rigidity. For a diagnosis of malignant hyperthermia to be made, at least 3 of the clinical findings must be determined. Dantrolene sodium is specific antagonist of malignant hyperthermia . However, it is not usually preferred by veterinary practitioners due to its high cost as well as the low incidence of the occurence of this complication. Therefore it is useful for alternative drugs such as a cepromazine, diazepam and alfentanil to be used for the treatment of clinical findings manifested during malignant hyperthermia . The purpose of this review is to share with colleagues the latest information regarding the treatment of canine malignant hyperthermia occurring in relation to general anaesthesia.