1. Department of Clinical Sciences; North Carolina State University; 4700 Hillsborough Street Raleigh North Carolina 27606 USA
2. Department of Microbiology; Pathology and Parasitology; College of Veterinary Medicine; North Carolina State University; 4700 Hillsborough Street Raleigh North Carolina 27606 USA
3. Animal Disease Diagnostic Laboratory; School of Veterinary Medicine; Purdue University; 1240 Lynn Hall West Lafayette Indiana 47907 USA