Hi guys. I have a 5 month old Border Collie bitch. She is absolutely good as gold for 90% of the time doing all the usual puppy things. But just recently she has started to become really aggressive towards me and my boyfriend and acting strange on her walks. When we walk her she will be fine up until a certain point where she will start jumping up trying to grab the lead, biting hands and growling. It's impossible to walk her like this. She has also started to bite us when she doesn't get her own way and it seems as though she really means it, she snarls and growls really viciously. We end up having to pin her down , like the mum would do, or put her in another room until she has calmed down. PLEASE HELP! Is it something we are doing wrong, is this normal for a BC pup or is it her with the problems. Bearing in mind we have stopped playfighting with her and are now trying to get her to sleep downstairs incase this is a dominance issue. Any comments will be helpful, thanks.