Our livestock guardian dog recently pulled a lot of feathers out of one of our turkeys, the dog was trying to herd it into its coop but the door was shut. On the one hand I was happy that the dog didn't kill the turkey, it built a lot of trust that our dog doesn't have the 'kill instinct' as she could have easily killed the turkey.
Can you see where the missing feathers on the chicken are?
I haven't been able to tell but it could have been one of the dogs. They are well trained but they of course are a more primitive breed of dog and have that kill instinct.