My dogs have always been unconventional breeds, if mutt is a breed. The current one's first retrieve consisted of swimming to a cripple, getting pecked on the nose, and swimming back.
The judge went out and "spoke" to the gunners, and they filled the next poor bird so full of lead that it's a wonder my dog could carry it.
My experience is that the girls stand a lot less nonsense from cripples than the boys. I have seen my oldest Lab, a cagey character, leap up in the air over a wounded bird to get behind it and grab it by the scruff. Then if they flap and quack too much she gives them a quick shake, "That's enough out of YOU, my fine fellow!" and they settle right down. A friend's little bitch will actually LIE DOWN on them until they quit fighting.
We use her to run down escapes from the crates because she is extremely soft-mouthed and won't muss a feather on a live bird.