Unanticipated hyperkalaemia and associated perioperative complications in three captive grey wolves (Canis lupus) undergoing general anaesthesia

Intraoperative hyperkalaemia has been described in dogs, cats, non-domestic felids and in a calf. This case series reports the occurrence and associated complications in three captive-held grey wolves anaesthetised for root canal treatment. Severe bradyarrhythmia associated with hypotension was detected in two cases before hyperkalaemia was confirmed. These also presented with signs compatible with malignant hyperthermia and rhabdomyolysis. In the third wolf, regular arterial blood gas analysis revealed a progressive increase in plasma potassium exceeding reference values 240 min after premedication. Hyperkalaemia was treated symptomatically with standard protocols, and the recovery was uneventful in all three wolves. The cause of hyperkalaemia in the described cases remains unknown and is most likely multifactorial. Prolonged recumbency, long anaesthetic duration and the administration of alpha(2)-adrenoceptor agonists are potential influencing factors. Additionally, malignant hyperthermia, rhabdomyolysis, acidaemia and drug effects are discussed for their potential of causing the described intraoperative hyperkalaemia.