1. Department of Veterinary Pathology, University of Liverpool, Liverpool, United Kingdom.
2. School of Biological Sciences, University of Liverpool, Liverpool, United Kingdom.
3. Department of Veterinary Pathology, and School of Biological Sciences, University of Liverpool, Liverpool, United Kingdom.
4. School of Biological Sciences, University of Aberdeen, Aberdeen, United Kingdom.
5. Faculté de Médecine Vétérinaire, University of Montreal, Montreal, Canada.