My out door feral cat has been coming in my house after having him outside for six years. But I noticed he has been shaking is tail sometimes. Does that mean he is spraying his mark. I would love to make him an indoor cat but I don't want him to spray. I do have an indoor cat also. He does have a clipped ear when he came to me 6 years ago. What can I do to stop him from doing that. Also it was a nice day out today and my indoor cat was getting along with the outside cat when I had the screen in. They know there smells . I am wondering if they would fight if I had them in the same room?