I think all animals (at least mammals) have unique facial features. With some, it's the color of the fur or skin. Take the tiger for example, each one has a unique stripe pattern. Although to most humans every dog of the same breed looks the same, if you spend enough time around a bunch of them you'll notice slight differences in the shape of the ears or the shades of colors in their eyes. These are just a couple of examples. If we could view the world from the eyes and minds of the animals, they might think all humans look basically the same.