1. Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California 95616, USA;
2. Departement Pathologie Generale Infectieuse et Parasitaire, Ecole Nationale Vétérinaire de Nantes BP 44307, Nantes Cedex 03, France;
3. Department of Clinical Sciences, School of Veterinary Medicine, Colorado State University, Fort Collins, Colorado 80523, USA;
4. Department of Biology, Colorado State University, Fort Collins, Colorado 80523, USA;
5. Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California, Davis, California 95616, USA;
6. Veterinary Teaching Hospital, School of Veterinary Medicine, Colorado State University, Fort Collins, Colorado 80523, USA;
7. Department of Statistics, Colorado State University, Fort Collins, Colorado 80523, USA;
8. Department of Pathology, Colorado State University, Fort Collins, Colorado 80523, USA; ,
9. Koret Veterinary Teaching Hospital, School of Veterinary Medicine, The Hebrew University of Jerusalem, PO Box 12 Rehovot 70600, Israel;
10. Animal Dermatology and Allergy, Loomis, California 95650, USA;
11. Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California, Davis, California 95616, USA