[1] Univ Guelph, Ontario Vet Coll, Dept Pathobiol, Guelph, ON N1G 2W1, Canada
[2] Royal Univ Hosp, Clin Microbiol, Saskatoon, SK, Canada
[3] Saskatchewan Hlth Author, Saskatoon, SK, Canada
[4] Univ Saskatchewan, Dept Microbiol & Immunol, Saskatoon, SK, Canada
[5] Univ Saskatchewan, Dept Pathol & Lab Med, Saskatoon, SK, Canada
[6] Univ Saskatchewan, Dept Ophthalmol, Saskatoon, SK, Canada
[7] Auburn Univ, Dept Anat Physiol & Pharmacol, Auburn, AL 36849 USA
[8] Univ Copenhagen, Fac Hlth & Med Sci, Dept Vet & Anim Sci, Stigbojlen 4, DK-1870 Frederiksberg C, Denmark
[9] Royal Vet Coll, Dept Pathobiol & Populat Sci, Hawkshead Lane, Hatfield AL9 7TA, Herts, England
[10] Cedarview Anim Hosp, 4100 Strandherd Dr,106, Ottawa, ON K2J 0V2, Canada
[11] North Carolina State Univ, Coll Vet Med, Dept Mol Biomed Sci, 4700 Hillsborough St, Raleigh, NC 27606 USA
[12] Univ Copenhagen, Fac Hlth & Med Sci, Vet Clin Sci, Dyrlaegevej 16, DK-1870 Frederiksberg C, Denmark
[13] Colorado State Univ, Dept Clin Sci, 300 West Drake Rd, Ft Collins, CO 80523 USA
[14] Univ Penn, Sch Vet Med, 3800 Spruce St, Philadelphia, PA 19104 USA
[15] Univ Calif Davis, Sch Vet Med, Dept Med & Epidemiol, 2108 Tupper Hall, Davis, CA 95616 USA