Found this bone out on a back road and was wondering what it was, since it was kind of large. I didn't have a ruler with me, but I figure the bone is just about 10 inches long and maybe about an inch or two thick. If it helps with identification, this area is coastal south Texas.
Horse femur have a tubercle about a third of the way down for muscle attachments, so not a horse. Cattle would normally be much bulkier than this, 3 inches or more thick. White tailed deer, just about right