I have two elderly males aged twelve and thirteen who are still capable of showing an interest in the ladies and last week I had them jabbed with something called Suprelorin, which is a 'chemical' castration. It lasts approximately six months and has the same effects as surgical castration, except of course for the removal of their 'bits' (which do actually shrink a bit, regaining their normal size if you don''t have them re-jabbed).
For anyone who is considering castration but not sure if it will help their particular problem (for instance if you have an aggressive dog) this might be a good way to find out if castration will help. The cost is around £40 - £45. Mine were done because I have two *** who are due to come in season anytime and I do not want any accidents, as they are closely related. It might also be handy if you have a male and a *** that is going to be spayed but you want her to have a season first, so having the dog jabbed would allow you to let the *** have a season first.