1. Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan.
2. Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio.
3. Department of Animal Science, College of Agriculture and Life Sciences, North Carolina State University, Raleigh, North Carolina.
4. Food and Drug Administration, Center for Veterinary Medicine, Office of Research, Laurel, Maryland.