I have two male dogs a month apart in age. The eldest is one year and a half his an intact German shepherd. The youngest one is one year and five months his an intact kelpie. These two dogs have been living together for about 3 months. We got the German shepherd first about 7 months ago. We haven't really had an issue until recently. They have had 4 fights in the past week all while I am alone with them. They start really fast with no warning and have been getting worse, we have to intervene and they still don't calm down for ages. The last fight went for quite a while as they wouldn't stop and I was on my own when it first started. They are seriously injuring each other now and the kelpie is at the vet tonight getting stitches and desexed. It seems he starts the fights and the shepherd usually submits but he isn't anymore and neither will the kelpie. What can I do to bring them back to friends again. I cannot tell who is alpha between them as they both have very strong personalities and show signs of alpha in a different way.