How do you tell how old a fawn is?

Well you may look at its spots and if they are starting disappear it is probably an older fawn. You may also be able to tell by the size of their hooves or antlers, if any antlers. With dogs they tell how old they are by their teeth, you may be able to do this with deer, but I really have no idea. That is really all I can think of, I am southern and know some about deer but this is just an odd subject.