1. Department of Veterinary Clinical Sciences; University Veterinary Centre (Camden); NSW 2570 Canberra Australia
2. Veterinary Informatics and Epidemiology; Department of Veterinary Clinical Studies; University of Glasgow Veterinary School; Bearsden Glasgow G61 1QH
3. Department of Statistics and Modelling Science; University of Strathclyde; Livingstone Tower, 26 Richmond Street Glasgow G1 1XH