hi mate,
twenty years ago i had an english bull terrier that started to get real nasty with other dogs so i followed the same train of thought as yourself and went to the vets he told me that it may or may not have the desired effect but as a try measure he gave him a hormone jab that he said after a few days to get into his system would have the same effect as castration and would last a week or two if it did the job then ok go ahead with the op.
one week later the dog was a changed animal so great thinks me its worked, that afternoon i had to go out so i put him in his pen along with my 5 month old whippet bitch that he had known all its short life, when i returned an houre later the pup was dead, so the next day my best mate followed him it was the hardest thing ive ever had to do but it had to be done.
take from this sad story what you like maybe this maybe that but to this day if any dog i own shows aggression that is unpredictable its history, as ive learnt my lesson.
all the best
jimmy