This atlas consists of 9 chapters, showing common diseases in Canadian lamb feedlots of the cardiovascular (heart and circulatory), respiratory (lungs), hepatic (liver), urinary (bladder, kidneys), nervous (brain), integumentary (skin) and musculoskeletal (muscle, bones), reproductive (uterus, neonatal lambs) systems, and miscellaneous. Images of gross pathology lesions are presented along with histopathology pictures showing microscopic lesions in tissues. In most cases small ruminant veterinarians will make clinical diagnoses based on gross pathology lesions observed during a necropsy. In cases where the veterinarian is not sure of a diagnosis, they may submit tissue samples to a pathology laboratory for confirmation of a diagnosis by a pathologist. The histopathology pictures are there to remind veterinarians what the lesions look like microscopically in various disease conditions.