Ceeby was six months old when I got Silk, an adult female, he is not the least bit jealous of her but he will soon be seven months old and I have a new girl that will be eleven weeks on Saturday. he is so jealous of her it is funny to watch. we have to make sure to give him extra loving every day. BUT, they are great friends and play alomost constantly. i have to pick her up and hold her just so she can get a couple of minutes rest when they get to going. Even Silk, who would never play, is getting into the act. Something to see the three of them playing together everyday. As far as the crate, I don't crate mine but they are gated in my living room.