I read a comment about nevertheless tabbing a dog's collar. Very true. But what do you do? I just read about breaking up a dog fight/attack.
First tip was hose them down, distract them.
Second, physically block them from their target with a cushion, wood, etc.
Last ditch effort is grab their hind legs at the hips and swing them around and away. Depending on the dog, all it takes is being removed from the target.
Not sure how handy these tips would be if a chicken ended up in a dogs mouth, but good to know in case they get to your dog, or god forbid, child. Granted if the later where to happen, I think even I would be all for shooting the dog.
Not chicken related, but I was walking my greyhound and we got rushed by two shepherds. I was distracted at the time and instinctively just started shouting at the dogs as they approached and charged back a bit. They definitely weren't expecting that and backed up and left us alone. I suspect they just wanted to bark and no actually aggressive intentions were there, or that tactic would have gotten me and my dog bitten, but it also potentially saved us from that happening.