1. These authors contributed equally.; Laboratory Animal Resources, Colorado State University, Fort Collins, Colorado
2. Comparative Medicine Research Unit, School of Medicine, University of Louisville, Louisville, Kentucky
3. Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado
4. K. L. Maddy Equine Analytical Pharmacology Laboratory, School of Veterinary Medicine, University of California, Davis, California; Department of Veterinary Molecular Biosciences, School of Veterinary Medicine, University of California,
Davis, California
5. Laboratory Animal Resources, Colorado State University, Fort Collins, Colorado; Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins,
Colorado