I have two 30 lb terrier mutts that are about 2 now. We had a problem with them fighting if separated, sick, or injured when they were a year old. We left them with my parents who have two dogs as well, and we have not had the same problem since.
Recently, we were at my mother and father in-laws house and a fight broke out. Our more dominate of the two snapped at her cousin for trying to hump her. The less dominate of my dogs leapt at her sister and started a fight. We were able to stop the fight immediately and calm them within a few minutes. We then distracted/reintroduced the girls by making them do tricks for treats.
I have also noticed the less dominate dog snap at her sister if she acts out at strangers who she has already accepted.
We have put the alpha dog techniques into place and they have helped a great deal but we need a little extra help now. Any suggestions?