I have a terrier cross neutered male age 4. We've had him from about 1 year old - he was a rescue dog. He has always been "challenging", and just when you think you got it cracked, he goes and does something stupid....! His problem seems to be with other males if they've not had the op - the only reason I can think is that he sees them as a threat, and gets in there first before they do?? There's lots of noise, posturing and he then pins them down. He never bites, it's just noise, but it's still horrible. I always will put him on the lead if I'm unsure about the other dog- the problem we have is that there are so many dogs near to where we live, and we are right by two big parks. Has anyone else experienced this, and if so, how do they deal with it? Like I say, he only does it with unneutered males!