ihave a 12 month old border collie which i have had since she was 6 weeks old.9 months ago we took on a collie cross.the dogs both female got on well until around 6 weeks ago they had a terrible fight which we had to split up,my boyfriend got bite by the older dog.and now and then they start again,my son has been scratched seperating them.why would they start doing this?what can we do to prevent this from happening?

Hi,
Have you any idea what started the fight? Are either of them spayed? Was one coming into season when they fought? Unfortunately, when two bitches fight for real, they are far more serious about it than two dogs would be, and they may never forgive each other.