In my opinion, all living things are to have equal rights. Just the other day, I picked up a seagul with a broken wing on the side of the road. I called the humane society in my region. Told them I had found a bird with a broken wing and they were willing to come pick it up till I told them it was a seagul. Then the guy told me, oh it's only a seagul, well we won't pick him up......
People don't mind to let animals die when they don't associate with it. But if I would have said I found a night owl, they would have came. Why? Doesn't a seagul deserve as much respect as a night owl?
So in my opinion, if we feed dead rats or mice to our snakes, then I do not see the problem in feeding DEAD pups or kittens.