I have two male shih tzus both are un neutered, from the same breeder but no blood ties, one of them turned one years old this june the other just hit one in august. Me and my girlfriend share responsibility for both of them and for the past 9-10 months they have been great dogs but like a flick of a switch fir the past week or so they are constantly fighting each other and its that bad snarling fighting that got me a small bite on my palm trying to break it up. Just yesterday 9/5/15 they couldn't go anywhere near each other before breaking out in it again. I couldn't even walk them close to each other to try and alleviate the tension.
A little more background onto the situation with them is that they always share a crate and share food with little to no issues at all with the food. They take turns and get their fills from the same bowl. And rarely ever fight like this in the same crate and when they did it was over a treat i give each one of them but i have stopped that even since noticing it became a problem in the crate.
We also did bring in my cousins male yorkie for a few weeks to watch him while they went on vacation, for the most part it was great with the new dog in the house for that short period of time. No crazy fights like these if not but 2 occasions but very minor and the fighting stopped after it was broken up by us.
But nothing like how it is now. The past 72 hours have been the worst. To me it seems like the one dog who is younger and we bought first seems to be the one starting the fights and seeking them out and is being very territorial. I say that we bought one first because they were purchased within two weeks of each other after we realized that we couldn't leave the first guy home alone and it was recommended to try two and we liked the idea and always wanted two dogs. It worked perfectly until now.
I honestly have no idea what to do, ive read so many different sites on how to stop this from happening after the first fight breaks out. Ive tried praising good relaxed behavior. Removing all toys and treats from the situation they might be fighting over. Showing each dog love and affection equally. Taking them on walks next to each other but that didnt work at all as i stated earlier. I have had to resort to finding an obedience trainer who cant see us till this monday at 5 but lord knows if these guys will make it that far. Please please help. Thank you all so much in advance.