[SnoopZ]

This might help. http://www.penninevets.co.uk/neuter.php

Dog - Male (Castration)
Castrating a male dog is not cruel, they do not need to feel a "whole dog" and they do not need to mate once in their lifetime. An uncastrated, entire male dog is at a high risk of developing prostate problems in later life, will be more aggressive, more difficult to handle and bigger. He is also more likely to escape from your garden and wander the streets. If you are wanting a friendly, easy to handle family pet, our advice is to castrate your dog before one year old, although it is advised at any age. The operation can be done from 6 months old.