When I was a kid, we had a dog who adopted an abandoned kitten, who was little enough to require bottle feeding. Other members of the family would have to distract the dog while I crawled into the dog house to retrieve the kitten for feeding, since the dog would not let us get close to the kitten - she was extremely protective of him.
I currently have a dog who nursed an orphaned raccoon. Thank you for reminding me to give her a special treat on this Mother's Day.