1. Department of Clinical Sciences and Services, Royal Veterinary College, University of London, Hatfield, Hertfordshire AL9 7TA, UK
2. Paragon Veterinary Referrals, Wakefield, West Yorkshire WF1 2DF, UK
3. Department Clinical Sciences, Faculty of Veterinary Medicine, 3584 CL Utrecht, The Netherlands
4. Department for Small Animals, Vetsuisse Faculty, CH-8057 Zurich, Switzerland