[1] Vale Referrals, Dursley GL11 6HF, Glos, England
[2] Massey Univ, Sch Vet Sci, Palmerston North, New Zealand
[3] VetCT, Broers Bldg,21 JJ Thomson Ave, Cambridge CB3 0FA, England
[4] Univ Vet Sci Brno, Fac Vet Med, Brno 61242, Czech Republic
[5] Univ London, Royal Vet Coll, Pathobiol & Populat Sci, Hatfield AL9 7TA, Herts, England
[6] Harper & Keele Vet Sch, Newcastle ST5 5NS, Staff, England
[7] Cornell Univ, Coll Vet Med, Dept Biomed Sci, Sect Anat Pathol, Ithaca, NY 14850 USA