Report Aggression with no sign of relief in General Border Collie Discussion Posted February 6, 2019 Thank you all so much for the input... certainly some interesting points and to be honest... a lightbulb moment for me thanks to Dinkle. Dinkle, you said "To me it would seem that your boy's problems are rooted in this. Your boy has been pestered and bothered by the pup and you've allowed her to do this (by the sound of it) to the point where he has lost all faith and trust in you. He's had to start assuming the leadership role in the house as he didn't see you as doing so. He even objects to you telling her off now as he sees it as his job! He's at an age, just approaching maturity, when he's very vulnerable to any changes in the pack dynamic." That to me is a lightbulb moment... and could be a major instigator. When the other dog was a puppy they are so cute and jumpy and mouthy and bitey... but cute and you think it's all in play... but Kobe may not have seen it this way and now his behaviour is taking a leadership role. Thank you so much for that insight... really invaluable. P.S... no, not from the UK, I'm from Australia. jami74, you mentioned taking him away or taking the other dog away... this is happening. in 2 weeks we are taking him for a "weekend away", and we are looking to send the other dog to relatives for 2 weeks. This will give us a much better idea of where we stand. Sue R, you mentioned vet check, yes we have done this, had all is blood tested, thyroid etc looking for abnormalities but all came back normal. Eye sight has been checked and all ok. Denice, we have been in touch with the breeder and also the owners of his brothers and sisters and none of them are having the same issues. Again... thank you all so much for your advice!!!