1. Department of Clinical Sciences, Colorado State University, 300 West Drake Road, Fort Collins, CO 80523, USA
2. Bristol Veterinary School, University of Bristol, Langford, Bristol BS40 5DU, UK
3. The Linnaeus Group, Shirley B90 4BN, UK
4. Hospital Clínic Veterinari, Universitat Autònoma de Barcelona, 08193 Bellaterra (Barcelona), Spain