1. 1. Department of Comparative Medicine, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37901, USA
2. 2. Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37901, USA
3. 3. Department of Pathology, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37901, USA
4. 4. Post Office Box 1143, Collegedale, TN 37315, USA