Affiliation: | Royal Veterinary College, Hawkshead Campus North Mymms, Hatfield Herts AL9 46TA, UK,;University of Strathclyde Livingstone Tower, 26 Richmond St Glasgow G1 1XH, UK,;Ecole Nat. Veterinaire de Toulouse 23 Chemin des Capelles 31076 Toulouse cedex 03, France |