[1] Univ Guelph, Ontario Vet Coll, Dept Pathobiol, Guelph, ON N1G 2W1, Canada
[2] Artemis Technol Inc, Guelph, ON, Canada
[3] Clemson Univ, Dept Anim & Vet Sci, Clemson, SC 29634 USA
[4] North Carolina State Univ, Coll Vet Med, Dept Populat Hlth & Pathobiol, Raleigh, NC 27607 USA