1. Department of Veterinary Anaesthesia and Analgesia, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh EH25 9RG, UK
2. Equine Clinical Studies, Diagnostic Imaging and Anaesthesia, UCD School of Veterinary Medicine, University College Dublin, D04W6F6 Dublin, Ireland
3. Department of Small Animal Surgery, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh EH25 9RG, UK
4. Department of Veterinary Medicine, Queen’s Veterinary School Hospital, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK