Yogi, I hate to tell you this but I was told by a GSD rescue that I couldn't have a dog from them because I had sheep and that GSDs were not to be trusted around sheep!
You should have seen her face when I said, "German SHEPHERD Dog - what the heck were they bred for?"
Lol! Both hysterical and ridiculous! Is that the dog from the story? Looks a lot like my boy! It's always funny how much the lambs LOVE the dogs isn't it?
That is our bottle lamb that lived inside for a good 6 months. She was born at <3lbs and had a rough start, so obviously vulnerable. Our other dog wanted to eat her but is well behaved and while they were supervised to be safe they were good friends. Honestly Logo (GSD) really didn't need supervision, in fact he would "protect" her from the cats lol. I trust him as much as you can trust anything, sadly it's unlikely I will have children in his lifetime as he would be the best nanny!
The lamb and him are still good friends though my mother cruely forced her to go back outside with those horrible "sheep" creatures. Poor thing can't figure out what she did to deserve such treatment!
Every year I have pictures of lambs climbing all over him. Vicious! I see yours is equally vicious and can't be trusted!
But to keep this on track, this is temperament and training and environment. We have a small "farm" and lots of animals and the dogs interact with them all AND they were all raised like this. That's just how we, and they, live. For animals that aren't used to it and don't have that as the norm it can be a big transition, and a dangerous one.
I would trust a farm dog to go into my flock. I wouldn't trust a pet that wasn't exposed to them. Same with the horses, except that is more for the dogs sake!
My parents got a new tenant who brought her dog and those were my conditions. One, she get along with my dog and not stress him out (he has health issues) and two, she be ok with the "livestock". There are also legal issues if the dog gets hurt, or in the OPs situation if the dog were to hurt someone elses animals.