1. The Queen Mother Hospital, Department of Small Animal Medicine and Surgery, The Royal Veterinary College, University of London, Hawkshead Lane, North Mymms. Hatfield. Hertfordshire AL9 7TA.
2. *Department of Pathology and Infectious Diseases, The Royal Veterinary College, University of London, Hawkshead Lane, North Mymms. Hatfield. Hertfordshire AL9 7TA.
3. Department of Pathology and Microbiology, Comparative Pathology Laboratory, School of Veterinary Science, Langford, Bristol BS18 7DU