The behaviour of one of my cockers is causing me some concern and I believe it has all stemmed from his early neutering(he was done at 6 months)  He turned 2 back in May and ever since the op, he has been pestered by male dogs which has now caused problems with his nature. He put up with it for ages and it was only back at the beginning of the year, that he snapped at one of the dogs for the first time. I was a bit shocked at the time as he has(or had) a superb temperament but i just thought, fair enough, he's just telling the other dog that he isn't happy in their own language. But now this behaviour is becoming more common and just recently, he snapped at a dog we were out with as she got too close to a hole he was digging in the sand  He doesn't behave like this all the time, so I'm thinking there may be hope for me getting my nice dog back. Just recently at training, he snapped at one of the dogs for sniffing at his back end for too long(he rolls on his back when they do this - not sure if this is significant) but the next time they saw each other, they were rolling about playing with one another like they were best friends. I read an article that said some dogs who suffer from this can have crystals in their urine and/or a bladder infection with no other symptoms, so a urine sample has been sent to the lab for comprehensive analysis just in case, but i know its a long shot.  I got him at 7 weeks and he has been very well socialised, completely bomb proof in fact, nothing fazes him but I do want to nip this recent behaviour in the bud. He has attended training class since he was 12 weeks old and loves it.

Look forward to hearing any thoughts/suggestions 

This being pestered by other dogs is one of the problems that can occur in a neutered dog and the vet can give you hormonal tables to help with the problem of feminisation but they are expensive and are of course a type of steroid that replace those that the dog can no longer make for themselves, so do require careful thought before starting on this HRT

This happened to a lovely mEnglish Springer at our training class.  It made his life a misery as he would be pestered by every dog he met and it terrrified him.  He had to be kept on a lead all the time, and it was only at the club he eventually learnt to trust the dogs he met there whose owners ensured he didn't get pestered by them.

so lots of positive expereicnes in a controlled way with other dogs to ensure he doesn't have to protect himself.