1. Department of Comparative Biomedical Sciences, Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield AL9 7TA, UK
2. INTHERES, Université de Toulouse, INRAE, Ecole Nationale Vétérinaire de Toulouse, 23 chemin des Capelles-BP 87614, CEDEX 03, 31076 Toulouse, France
3. Department of Clinical Sciences and Services, Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield AL9 7TA, UK