they are very soft actually, if you pinch the hoof you can squish it a little bit. I wouldn't worry about cleaning it at all, it wouldn't be cleaned if he was fending for himself :wink:
We had one laying around in the kitchen here for about 4 days, he'd chew on it for a while, tear some fur, and skin off, eat some of the hoof, leg, meat, etc and then at night i'd just put it back in the fridge :lol: