All training, whether slavegirl or animal, requires the Master (Owner) prove to be dominant. All animals have a method of deciding the "pecking order", be it dogs, chickens, chimpanzees. The simpler animals like chickens have simpler methods. Actually that's where the term 'pecking order' came from.
If you have a dog that rolls onto it's back when you approach, it's not to have it's belly rubbed because it feels so good. It's the dogs way of showing you that it is yours to command and the dog is surrendering everything to you.
The whole process is much more complicated that this. Whole books have been written on the subject (not by me), so covering it here makes it sound simplistic.
Yours to Obey
Pttwyn