1 Small Animal Clinical Sciences, PO Box 100116, Gainesville, FL 32610, USA. Electronic address: stonea@ufl.edu.
2 Department of Population Health and Reproduction, School of Veterinary Medicine, Department of Public Health Sciences, School of Medicine, University of California, Davis, 1089 Veterinary Medicine Drive, Davis, CA 95616, USA. Electronic address: phkass@ucdavis.edu.