Intra-anaesthetic asystole in a Bulldog during positioning for brachycephalic obstructive airway syndrome surgery

A male English Bulldog, aged 2.5 years, presented for brachycephalic obstructive airway syndrome corrective surgery for treatment of ventilatory difficulties and castration. The dog experienced asystole twice during positioning for surgery, suspected to result from the maxillomandibulocardiac reflex, a version of the trigeminocardiac reflex. Procedures were postponed and the dog was allowed to recover from anaesthesia. Echocardiography, electrocardiogram and 24 hour Holter monitoring were unremarkable. As ventilatory compromise persisted, the procedure was attempted again. Despite a period of severe bradycardia with intermittent sinus arrest after premedication, the dog was anaesthetized, underwent surgery and recovered. On follow-up 1 year after the procedure, the dog showed an improvement in respiratory effort and overall quality of life.