I've noticed that mother animals have a tendency to want to adopt any type of infant. I've heard of mother cats actually nursing ducklings or baby chicks... any cute little round fuzzy creature who needs a mama. Okay, so human babies aren't so fuzzy... but the theme is still the same as they are little, round and cute. The mama instinct is quite powerful and it can even cross genders a little bit at times as well. I have personally seen neutered male cats trying to 'nurse' baby kittens, with the male cat and the kittens thoroughly enjoying the experience. So, while it is a bit surprising to hear about a human baby suckling on a dog, it makes sense in a way, because mama animals are very protective of babies, and the more, the merrier. They will even adopt other babies because they just can't get enough of those warm, squirming little guys. In situations where there are multiple mother cats, I've seen the mama cats sharing babies, nursing whoever shows up at the lunch counter without regard to who actually belongs to whom. It's really quite interesting how the mothering instinct takes over and causes them to help out anyone in need like this.
