I have a 1 1/2 yr old shih tzu mix female and got a 3 month old male shih tzu 4 days ago. Even though it's only been a few days, the fighting between them has me worried. The two dogs both seem to be trying to show dominance by holding the other down and trying to mount the other. The new puppy tries to take toys from the female, and outside in the yard, it is not a problem. They also engage in playful fighting out in the yard. 

In the house, whenever we show attention to one of the dogs, the other comes over to jump on the one getting attention. Both dogs instigate play fights, but they usually get carried away and end with the female nipping too hard and the puppy cries. Sometimes the female will just go after the male without warning. I've tried time outs by holding the female in another room, but it's not really changing her behavior.

 Does anyone have any suggestions for what I can try to ease this transition? Fortunately, they will stop fighting if I raise my voice and I can then move them away from each other. I have also been told that dogs play rough and that if I just let them "fight it out" they will fix it on their own. I'm just not comfortable with watching what I think may be 2 alpha dogs fighting and potentially getting hurt. Is there anything I can do to prevent the fights altogether?

I would greatly appreciate any help you can give!!!!

Michelle U.