1. Department of Clinical Sciences & Advanced Medicine School of Veterinary Medicine, University of Pennsylvania Philadelphia Pennsylvania USA
2. Research Support Office Royal Veterinary College, University of London London United Kingdom
3. Department of Neurology and Neurosurgery Pieper Memorial Veterinary Center Middletown Connecticut USA
4. Section of Neurology and Neurosurgery Red Bank Veterinary Hospital Tinton Falls New Jersey USA
5. Department of Neurology and Neurosurgery Bush Veterinary Neurology Service Springfield Virginia USA
6. Department of Pathology School of Medicine, University of California San Diego La Jolla California USA