I'm just wondering the average size of an adult Guinea Pig. My big male weighs 2.5 lbs., he's short and has the cutest little potbelly! I figured he was to his full size. Then we went to the children's zoo and saw the Guinea Pigs there. They seemed like they were twice his size/length! What is the average size of an adult pig? And do the short haired varieties get as big as the Abbys? I have one abby (my big one) and two short haired.