1. W.R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine; University of California; Davis, Davis California
2. Department of Medicine and Epidemiology, School of Veterinary Medicine; University of California; Davis, Davis California
3. Department of Veterinary Molecular Biosciences, the K.L. Maddy Equine Analytical Chemistry Laboratory; School of Veterinary Medicine, University of California; Davis, Davis California
4. Division of Animal Sciences; University of Missouri-Columbia; Columbia Missouri