I can only tell you my experience, and not a general or typical thing. I had an intact male chihuahua that was 1.5 years old, when I got an 8 week old chi mix puppy. The older one always had to be in charge, but all was ok until the puppy was sexually mature at around 7+ months old.
What happened, happened suddenly. They got into a fight for no reason. It wasn’t over food, toys or my attention. They simply looked at each other and lunged at each other. It was a very severe fight with both dogs being injured.
I separated them, waited a couple of hours and let the puppy out of the bedroom. As soon as as he saw the other, right back at it they went. Within 24 hours I had a rescue come get the baby. They couldn’t tolerate each other at all! If I came out of the room carrying the younger one, the older one would just stay at my feet and whine and whine. If I got close to putting hm on the floor, he was attacked by the other one.
Like I said, it’s just my experience, but I will never again have two, same sex, unaltered dogs in my home. I’m impressed other people have had little or no problems with it, but I’ve also heard too many other stories like mine.
I do wish you the best of luck with whatever you decide. By the way, the puppy was 25% chi and 75% tpoo.
Sent from my iPhone using Tapatalk