They make cat doors that will only allow the cat wearing the special collar to get in. Maybe you should get one of those so that Raj can go in, but Otto can't go in and get stuck.

Kristin - they do??! Cause it really freaks me out that Otto could potentially get stuck if we're away for a night or something. We've thought about just closing it off to both of them, but Raj likes to go in it as his "fortress of solitude".

Look at something like this.

Kristin - Turns out that won't work for us. Unless there is a way that it actually opens the flap (like a garage door opener). nbh found out how Otto gets in. He follows Raj closely and then grabs the door with his paw while raj is partly through. He then goes inside. But he can't figure out how to leave unless Raj leaves at the same time. *sigh*

Have you tried teaching him to go through on his own? Put him on one side of the door and then try tempting him with his favorite treats to push through the flap on his own. I don't know if this would work but it might be worth a try.

Donna - We haven't tried that yet, mainly because he wasn't going in until recently. We figured he'd learn or he wouldn't. Now we've got this in between and we need to do something about it! We'll try that next. As you know, he startles easily so it's hard to get him to focus on something.....

I suspect that at some point, if he is stuck, his hunger will overcome his, well, lack of IQ.