1. Department of Clinical Sciences (Pressler, Vaden), College of Veterinary Medicine, North Carolina State University, 4700 Hillsborough Street, Raleigh, North Carolina 27606; the
2. Department of Small Animal Clinical Sciences (Lane), College of Veterinary Medicine, University of Tennessee, P.O. Box 1071, Knoxville, Tennessee 37996; the
3. Department of Medicine and Epidemiology (Cowgill), School of Veterinary Medicine, University of California, 1 Shields Avenue, Davis, California 95616; and the
4. Pulmonary Toxicology Branch, Experimental Toxicology Division (Dye), National Health and Environmental Effects Laboratory, United States Environmental Protection Agency, 86 T.W. Alexander Drive, MD-82, Research Triangle Park, North Carolina 27711
5. From the