Neutering practices in Hong Kong?

We recently adopted a little Pomeranian who was born in Hong Kong. He was neutered there, but the old owner told us that he still had his, well, you know whats. I wondering if he only had a vasectomy or if they do something else? I'm unaware of their practices. If he did only have a vasectomy should we have him completely neutured? Lately he's been rather protective and I wonder if this has anything to do with it.