Male dogs are castrated because there is 100% certainty that it has worked.
If they had a vasectomy there are certain tests that need to be done after the operation to be sure that it has worked. These tests are the same as the ones for humans, involving bodily fluids (ask Alan if you don't get my drift !).
I volunteer at SARA and I knuckle down and do anything and everything required including being an Excrement Eradicator. But, a girl has standards, and I would certainly draw the line on performing THAT task !!
Don't worry about Guido. If you drop him off at 8.30 in the morning, when you pick him up at 1pm he will be up and running around. It is a very simple operation and will hardly affect him at all. You probably won't notice any difference apart from a bit of silver spray around his nether regions.
If it really bothers you and you want him to be a bit more macho, treat him to some Neuticles :
visit the merchandising mart for the key ring or "Must Have" necklace........