I have a male Labrador and today I have my mothers male CKCS they are biting each other and the CKCS is growling (but he does that when he plays with his toys) I have now got a gate between them but they are both still playing? with each other though. They have wagging tails and no hackles. But we have had one yelp. Are they playing or fighting? and how do I tell thde difference.