1. From the Matthew J. Ryan Veterinary Hospital of the University of Pennsylvania, 3900 Delancey Street, Philadelphia, PA 19104. Dr. Menzies' current address is the Veterinary Teaching Hospital, Faculty of Veterinary Medicine, PO Box 57 (Koetilantie 4), FI-00014 University of Helsinki, Finland; and, Dr. Lewis' current address is NorthStar VETS, 315 Robinsville Allentown Road, Robbinsville, NJ 08691