1. Virginia Department of Game and Inland Fisheries, Richmond, Virginia 23230, USA
2. Current address: US Geological Survey, National Wildlife Health Center, Madison, Wisconsin 53711, USA
3. Virginia Department of Agriculture and Consumer Services, Warrenton Regional Animal Health Laboratory, Warrenton, Virginia 20186, USA
4. University of Pennsylvania, School of Veterinary Medicine, New Bolton Center Toxicology Laboratory, Kennett Square, Pennsylvania 19348, USA