1. Laboratory of Pathology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA
2. Department of Pathology, School of Veterinary Studies, Murdoch University, Perth, WA, Australia
3. Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA
4. Department of Pathology, New York State College of Veterinary Medicine, Cornell University, Ithaca, NY