1. Department of Biomedical Sciences and Pathobiology, Virginia-Maryland Regional College of Veterinary Medicine, Blacksburg, Virginia, 24061, USA
2. United States Department of Agriculture, Agricultural Research Service Livestock and Poultry Sciences Institute, Parasite Biology and Epidemiology Laboratory, Beltsville, Maryland, 20705, USA
3. Brook Run Animal Clinic, Richmond, Virginia, 23227, USA