My Boxer is fine with anything if I am around, he acts like he doesn't even notice them. If a dog happens to come up to the fence or someone he doesn't know comes up, he attacks the first thing he can get to ( I guess out of frustration), Usually its my doberman that he gets because... well she is there. So he will NEVER be allowed around any of my chickens unsupervised, to many variables and he is already half cocked. lol
My Doberman has a high prey drive.I have been slowly introducing her to the chicks... I was sitting right there with her on one side and the chicks right in front of me. I was watching EXTREMELY close cause I don't trust her, well she did it. She snatched up my silkie... I yelled "hey" she looked at me with 2 black little chick legs hanging out of her mouth. I told her to drop it and she spit out a sopping wet little chick that was traumatized. (Chick is now 7 weeks old.) SO I have decided she doesn't get near the chicks unless she has a muzzle on, just to be safe. I have already kicked around the idea of finding the biggest baddest, turkey, goose or whatever to pen her up with for about 5 minutes, put a muzzle on her and let that bird put the fear of God in her.... but I don't have a bird that could do it lol.
I think its to risky to leave a dog with an animal like chickens. A friendly game could turn into a blood bath very easily.
Now I'm not saying that there aren't dogs that can be left alone with chickens.... but I'm not going to trust any dog around my flock.