i would tell the man that a witness came to you saying they saw him hit the dog. you don't want people seeing someone treat a dog like that in front of the training center. just the right person might see him do it and think "it happend in front of a training center, it must be ok to hit my dog." she may be comming into heat. Gracie always gets a lil out of control when she's in heat, but she NEVER tries to bite anyone. if the dog was trying to bite him when he punched the dog explain to him that there are other ways to correct this behavior.

GOOD LUCK!