I have the same problem, my dad used to yell at my dog Missy all the time he might still yell at her while I'm not at home. When he would yell at her she would cower and run to my room with her tail in between her legs. Missy is a sensitive dog so just the slightest sound of irritation in your voice she will cower and roll over. I got my dad to stop yelling at her and smacking her by yelling at him and picking up Missy and bringing her to my room. Yes, it caused a lot of tension between me and my dad, we would get into huge fights over it, but in the end he realized I would not stand by while he mistreated my dog. My family dog Chase is like you Bonnie he doesn't mind it when he gets yelled at or punished. Just keep telling your dad that yelling and punishing the dogs are wrong and let him not that your not okay with it, hopefully he will soon stop. Good Luck Emily.