
Castration before maturity increases height, because it delays the closure of growth plates, so your dog is likely to be somewhat taller than he would otherwise. The same phenomenon is found in farm animals, and was remarked upon in the days of castrati singers. They too were renowned for being unusually tall. It also alters the pattern in which body fat is laid down.
Ram lambs, for example, are less likely to be castrated because of this. Although the animal is bigger (more carcass weight = good) there is more fat, which nowadays is unwanted, so the overall value at slaughter is less.