HI Ya
How old is your youngster? Do you know the size of the sire and dam? - You can sometimes estimate what height a youngster will grow from knowing what height the sire and dam are - but you can sometimes get a throwback from a distant relative which means the youngster may grow much bigger than the sire and dam - or in some cases be smaller than the sire and dam - I would have thought if he is aged 3 to 4 you not going to get much more growth out of him - he is more likely to fill out - if he hasn't already. From past experience it really does depend on the size of the sire and dam (and this is my own personal opinion) - although like I said above you can sometimes get a throwback. Hope this helps. :