How big will my puppy get?

[freckledimple]

I have a new puppy. He was dumped at my neighbors house and they gave him to us. We took hin to the vet and he said we have a healthy 13 lb 3 month old. There was no mention of what he might be, or how big he'll get. I was wondering if anybody had an idea on either of those issues.

This is our JD.