[1] Medvet Chicago, Med & Canc Ctr Pets, 3123 N Clybourn, Chicago, IL 60618 USA
[2] Univ Chicago, Pritzker Sch Med, Dept Neurosurg, Chicago, IL 60637 USA
[3] Royal Vet Coll, Dept Clin Sci & Serv, Small Anim Med & Surg Grp, Hatfield, Herts, England
[4] Univ Copenhagen, Fac Hlth & Med Sci, Dept Vet & Clin Anim Sci, Copenhagen, Denmark
[5] Univ Vet Med, Dept Pharmacol Toxicol & Pharm, Hannover, Germany
[6] Ctr Syst Neurosci, Hannover, Germany
[7] N Carolina State Univ, Coll Vet Med, Dept Clin Sci, Raleigh, NC USA
[8] Univ Minnesota, Coll Vet Med, Dept Vet Clin Sci, St Paul, MN 55108 USA
[9] Univ Georgia, Coll Vet Med, Dept Small Anim Med & Surg, Athens, GA USA