[1] Univ Leon, Fac Vet Sci, Dept Surg Med & Vet Anat, Campus Vegazana, Leon 24071, Spain
[2] Stanford Univ, Stanford Sch Med, Dept Neurosurg, Palo Alto, CA USA
[3] Retiro Vet Hosp, Madrid, Spain
[4] Univ Leon, Inst Biomed IBIOMED, Fac Vet Sci, Campus Vegazana, Leon 24071, Spain