[1] Texas A&M Univ, Coll Vet Med, Dept Large Anim Med & Surg, College Stn, TX 77843 USA
[2] N Carolina State Univ, Coll Vet Med, Dept Food Anim & Equine Med, Raleigh, NC 27606 USA
[3] Univ Minnesota, Coll Vet Med, Dept Clin & Populat Sci, St Paul, MN 55108 USA