Affiliation: | 1. Department of Clinical Veterinary Science , Langford House, Langford, Bristol, BS18 7DU, England;2. Department of Veterinary Clinical Sciences , Massey University , Palmerston North, New Zealand;3. Department of Veterinary Pathology and Public Health , Massey University , Palmerston North, New Zealand;4. 95 Uxbridge Road, Howick, Auckland, New Zealand |