He was at the vet not because of injuries from the dog (4 months young female but same size like him at the moment) but because they wanted to be sure he don't has broken ribs. It was not easy to get Olaf off the dog. He used all claws and all four fangs. But the dog also is fine. She didn't have to stay at the vet.
Thanks for the congrats. I think she won't purr if I tell her but maybe she doesn't hiss at me or she hisses less. :) Her name is Putzi. I was her cat sitter when her humans were on vacation for a week.
That's a weird story. They should have known better because the shelter's staff told them everything about Leo. And finally he was brought back by their secretary not by Leo's humans themselves. Never heard something stupid before.