1. Equine Referral Hospital; The Royal Veterinary College; Hatfield Hertfordshire AL9 7TA UK
2. Bell Equine Veterinary Clinic; Butchers Lane Mereworth Maidstone ME18 5GS UK
3. Department of Clinical Studies; Section of Biostatistics; University of Pennsylvania; School of Veterinary Medicine; George D. Widener Hospital for Large Animals; New Bolton Centre, Kennett Square West Chester Pennsylvania 19348 USA