Every warm blooded animal has enough brain matter to tan their hide....or so I'm told. I've personally never done it but use to have a friend that did. He was into the Mountain Man stuff and did it all the time. Years ago there was a guy on our deer lease that did something with the hides. He had them in a bucket soaking and the hair would come off. I don't remember what was in the bucket though. I did make a quiver from a beaver pelt long ago. I stretched it on a frame and scraped all the meat and fat off and kept it salted. Then made my quiver, but the hide was very stiff but that's the way I wanted it. Guess I'm not much help with the tanning part.