how to get my dogs to stop biting each other?

my two dogs, one 9, the other 2, are always play fighting. our 2 year old dog has bitten our 9 year old dog multiple times and has broken the skin, so hes had stitches multiple times, what can we do to prevent this from happening? and we have tried using a muzzle but that doesn't seem to work.

First of all, are they both guy dogs. Because male dogs will fight to tell the other one who is boss. If so you might need to get rid of one. I know it is hard but unless you like paying the vet bills you need to get rid of one. OR the little one might be toothing and needs something to bite. Try getting him new toys or something it can chew. Hope this helps!!

This does not sound like play fighting. My rule is if there is no blood then it is play. It sounds the the 2 year old is the dominant dog. You need to respect this. Feed him first. Let him out the door first. Pet him first. Stop them when they get too rowdy. My dogs have learned to stop playing if I walk in the room and tell them "enough" and stare them down. It took a while to get to this point. Clanging two metal pots together may be required to get their attention. Throwing a blanket on fighting dogs is also recommended. Do not touch them or you may be bit. It may take a while, but keep at it.Otherwise you will have to get rid of the younger dog.