In general I don't castrate my hounds other than for medical need. However my bitches are all spayed ( usually once retired) as there is enough evidence to suggest the more seasons a b itch has, the more the risk of a female cancer/pyometra. We never had a pyo in our girls and although we only had one with mammary cancer in her 13th year, that's something I'd not wish on my worse enemy. So yes, I go with spaying, if not castration. I'm sure my vet disposes of their reproductive organs in the normal way.
Another reason for spaying, for me, was not needing to confine them roughly every 8 months (my bitches' cycle) for 3 weeks with the accompanying angst for my males.
We had entire males and females but NO unplanned litters!!!