
Vasectomy and castration are very different operations. With Castration the Testicles are removed, taking awy the sex hormones, whereas in Vasectomy only the tubes carrying the sperm from the testes to the outside world are cut. The latter should have no effect on sex drive past the recovery stage.
Men are no longer castrated (sadly in some sex offenders cases), I think the last Eunuch in china died a few years ago, though the practice of castrating boys was common even inEurope in the middle ages.
For those who say prepubescent castration has no effect on a dog should read up on Eunuchs.
In many peoples expereience neutering a puppy at that sexy stage, far from removing the urge just seems to keepp them at that stae for good. A male I bred was castrated at 5 months old, and looks like a Eunuch (Lacks the male ruff, narrower in skull, and very gawky, but sadly has been allowed to get tubby), and is still as bad at mounting as when he was done, whereas his entire litter brother is a gentleman in this respect and looks like a male. Both work in competitive Obedience, so lack of training isn't the issue.