A 19-year-old Cob mare with atrial fibrillation (AF) presented for transvenous electric cardioversion (TVEC). Under general anaesthesia, three successive incremental electric shocks were given (total 750 Joules) and sinus rhythm was temporarily restored. After 13 seconds, AF recurred so a fourth shock (300 Joules) was given and intravenous (IV) amiodarone started. Shortly after, capnography revealed an acute drop in the end-tidal carbon dioxide, which was followed by agonal gasping. Echocardiography showed severe cardiac dysfunction. Successful cardiac resuscitation consisted, amongst others, of cessation of amiodarone, and administration of dobutamine and adrenaline. This case report highlights the importance of capnography as a non-invasive means of cardiac output monitoring in equine anaesthesia which definitely contributed to a positive outcome. It also emphasises the critical importance of early recognition and communication of complications within anaesthetic and cardiology teams.

Cases of intraoperative hyperkalaemia in healthy greyhound dogs under general anaesthesia have previously been reported in veterinary literature. This case report describes the identification and treatment of hyperkalaemia in an otherwise healthy greyhound undergoing general anaesthesia for a fracture repair. The clinical signs were sudden bradycardia and loss of P waves on the electrocardiogram waveform. Treatment consisted of intravenous 10% calcium gluconate, rapid recovery from anaesthesia, intravenous glucose administration and continued serum potassium monitoring postoperatively. Potential aetiologies of the hyperkalaemia are discussed. BACKGROUNDHyperkalaemia in dogs (defined as serum potassium >5.5 mmol/L) is a serious electrolyte disturbance that can pose a risk to life if untreated. 1,2 Maintenance of high intracellular and low extracellular potassium levels are necessary for cellular functions and cell membrane electrical gradient stability. The development of unanticipated hyperkalaemia during anaesthesia has been increasingly reported in dogs over recent years, 3,4 with consequences ranging from brady-dysrhythmias to cardiac arrest. Additional case reports of hyperkalaemia in greyhounds undergoing multiple general anaesthetics have been published, 5,6 along with a 2018 abstract proposing a higher prevalence of hyperkalaemia in greyhounds. 7 We report another case of unexpected intraoperative hyperkalaemia in an otherwise systemically healthy greyhound undergoing a fracture repair and discuss potential aetiologies and treatment options for this clinical presentation. CASE PRESENTATIONAn 18-month-old, female, neutered greyhound in good body condition presented for reduction of left-sided concurrent radial and ulnar fractures that had occurred 24 hours prior. The dog was previously a racing greyhound before being rehomed to the current owners and had no significant medical history. Treatment by the referring veterinary surgeon included external coaptation, methadone (Comfortan; Dechra UK) (0.3 mg/kg every 6 hours intravenously [IV]) and paracetamol (10 mg/kg every 8 hours IV). Preoperative plain radiography of the thorax and antebrachium showed no further radiographic abnormalities.

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