aggressive.? My partners dog is a 5year old pedigree border collie (male). his aggression started about 2 years ago and since then his has bitten my partner and myself and other members of the family several times ( and drew blood) for no apparent reason and will not obey me or my partner when he is being aggressive (growling, baring teeth, etc) I also have a border collie and she is 6 but she is really obedient and has never bitten anybody the whole time i have owned her so i know that it is not me doing something wrong otherwise mine would be the same and she is the opposite. Today he bit my partner so bad that he needed 2 stitches in his finger. For the most part he is a well behaved dog so i cannot understand why his behavior changes in a split second we don't want to put him down but cannot risk giving him to another family with the aggression he has in case he bites a child. what can I do?