I agree. He would have hurt her much worse if he wanted to. with that being said... you really do need to watch them for a while. Here's why... 1- If the puppy at some point decides she wants to fight for alpha position as she gets older, it would get nasty since she has already been hurt by him before. Small chance she would try it, but I've seen it happen before. 2- IS there anything medically wrong with your older dog? Many times a dog will bite because they are in pain and the younger dog hurt them by playing. Ex: sever ear infection and the puppy pulls on the ear. 3-a dog will warn another in a set series of events... low growl, louder growl, snarl, air snap, etc... they should do al these things before they actually touch the other dog. Since you werent in the room, it is possible this happened and your younger dog just doesnt have that inate ability to know when to stop. If that is the case, she will most likely get hurt again. Was she kept with her littermates until at least 8 weeks where she learned how to play? Many dogs taken from their litter before 8 weeks have trouble with this. They have to be taught how to play bite by their owner. If this is the case, she probably play bites you too hard too. Another option is that your older dog isnt doing all the warning signs before the actually bite happens. In that case, I think you should be correcting her. Either way, would talk to an animal trainer immediately. I had 2 goldens a few years ago, one being a foster that had been taken from her litter early and then not really socialized well. She didnt get the whole doggie play thing. She adored my other golden but accidentily ripped a hole in her neck. And IM talking big here. A grand surgery and 3 months of healing time was necessary before she was allowed near the dog again. Sometimes letting them work it out on their own means lots of vet visits... Good Luck. Keep us poted.