Why do dogs blink their eyes when you look at them?

Dogs have a reflective surface at the back of their eyes to increase their night vision. You may see this in other nocturnal animals such as cats, raccons, and even deer. When the light hits it at certain angles, you will see a mirror like reflection. Different animals have different colored reflections, often green or red, although deer tend to be silver. The purpose of this is to increase the light to the retina, which increases the night vision of the animal. I know the surface has a name, but I don't remember what it is called. I was a bio major 20+ years ago and some things have slipped away...Hope this is what you were asking.