
The problem with snipping a dog that already fears attack by other dogs, is that you have taken away what little confidence he had. His status is now lowered, he is apprehensive of other dogs because of past bad experience, and other males are inclined to treat him as a bitch, or their personal fag/Punchbag, knowing that he hasn't enough confidence to stand up to them. Also you may find other male dogws will try to mate him, and he probably realises their intentions are not honourable and growls in an attemp at warning them off.
We have a lovely Springer male at class, who was castrated at a young age as a matter of routine. His owner cannot let him off the lead in the park where there are other dogs without him being molested, as he is such a submissive soul.
When he first came to class this made him terrified of other dogs. Gradually under controlled exposure he has made a lot of canine freinds at the club, and can't wait to come to clas. He is slightly less frightened of dogs when out, but they still wnat to mate him, so he has to be kept on lead.