Can someone please give me a little advice, I have a 12 week old gsd bitch pup and I have just noticed that one of her pupils is fully dilated where as the other is not, I put my hand over them both to see if they reacted to the light change and they did but then went back as they were, one big and one little, is this normal in the breed or could it be a sign of something about to happen?? also could it be hereditary because i wasn't warned of this and its took me by surprise, thanks 

I would have her checked by the vet - pupils should be the same size in the same light.