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A 7‐month‐old, 12.2 kg, male, neutered, English bulldog with severe pulmonary stenosis and R2A right coronary artery anomaly was anaesthetised for placement of hybrid right ventricle to pulmonary artery stent. An alfentanil bolus (10 μg/kg intravenously) was used as premedication. Anaesthesia was induced with midazolam (0.2 mg/kg) and etomidate (1 mg/kg) intravenously, and maintained with sevoflurane in 100% oxygen. Perioperative analgesia was achieved combining locoregional techniques with intravenous analgesics. The main intraoperative complications were hypotension, bradycardia, ventricular premature complexes, ST‐segment depression and transient hypoxaemia. Lidocaine constant‐rate infusion (50 μg/kg/min) and magnesium sulphate constant‐rate infusion (5 mg/kg/h) were used to prevent arrhythmias during the cardiac manipulations and stent placement. Hypotension was treated with dobutamine and noradrenaline constant‐rate infusion. The use of different drugs and anaesthetic techniques (balanced anaesthesia) provided antinociception, muscle relaxation and appeared to be effective in preventing major cardiovascular complications.

Two 8‐month‐old Suffolk sheep, weighing 45 and 55 kg, respectively, were anaesthetised for an intrathalamic injection of an experimental drug. After an uneventful procedure and general anaesthesia using controlled mechanical ventilation, the sheep were weaned off the ventilator and allowed to breathe spontaneously with end‐tidal carbon dioxide (PE′CO2) levels remaining within normal limits. During recovery, intermittent apnoeic phases were observed with increasing PE′CO2 (>70 mmHg) and decreasing oxygen saturation of haemoglobin (SpO2) levels (90%–91%). The sheep appeared unresponsive, and reflexes were absent. This alternated with phases of normal mentation, normal reflexes and regular spontaneous ventilation, where ventilatory parameters improved. Tentative treatment to reduce intracranial pressure and administration of the opioid receptor antagonist naloxone were unsuccessful. Definite diagnosis of Cheyne–Stokes respiration is difficult but was suspected in these two cases; cerebral cortex damage, intracranial haemorrhage or opioid mediated respiratory rhythm disturbances are possible causes.

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