1. Scott‐Ritchey Research Center, College of Veterinary Medicine, Auburn University, Alabama 36849, USA,
2. Department of Pathobiology, College of Veterinary Medicine, Auburn University, Alabama 36849, USA,
3. Comparative Oncology Unit, College of Veterinary Medicine and Biosciences, Colorado State University, Ft. Collins, Colorado 80523–1620, USA,
4. Hill’s Pet Nutrition, Science and Technology Center, Topeka, Kansas 66601–1658, USA