Hi, I am having a problem introducing my new shih tzu(female) which is 2years old to my old shih tzu(male) which is 5 months old. Since the first day they are always fighting. I keep them in the living room but the problem is the new dog have to be always inside her crate because if she goes out, my 5 month old male shih tzu will start sniffing her first then he would chase the female everywhere it goes even if he sees that the female is already mad and eventually they would fight. It's been 2 weeks already, my 5 month old doesn't have any problems when the female shih tzu is inside her crate.