Can dogs get bed sores?

I just rescued a dog and he has sores on his right where he would sit. He also has them on his front legs. They are hard and callused no hair grows on them and they stick up a little bit and are about the size of a quarter. They dont seem to bother him much but they look really bad. I dont know the story on him I just rescued him so he may have gotten into a dog fight but do scabs turn into lumps like that? It almost looks like he had to sit maybe in a cage for a long time. Would that make sores like that. If anyone has any idea I would greatly appreciate it.