Our Maximus is now 15 months old. We had an issue with our other 2 dogs when we first got Max. Dexter (the oldest and a cavalier x poodle) immediately put Max in his place and they get on fine. Max is very respectful with Dexter and things are great.
However, Alfie (whippet x poodle) just thought "Yaaay, a new friend to play with" and he let Max get away with anything. Chewing his legs, tummy, neck and ears. I am very much a "let the dogs sort themselves out" kind of person as we had 5 dogs at one point and this method had always worked well for us.
However, Max got to about 8 months and got his big teeth. All of a sudden Alfie realised it wasn't quite so much fun being chewed so he started trying to tell Max off. Unfortunately, Max just thought he was playing so carried on.
We seemed to spend days just telling Max to leave Alfie alone..... This has resulted in poor Alfie's ears having a permanent kink in them from the constant scabs that formed where Max kept on at him.
Alfie does tell Max off but very half heartedly and we still have to keep an eye on Max to make sure he doesn't hurt poor Alfie.
We have had cockers before - but never one quite like Max