I have two (litter mate) almost 4 month old kittens who are V-E-R-Y interested in the doggy door. One went out once and we have since kept the doggy door closed off. As you can mention, this is far from ideal for our puppy dog! In addition, any time we open the door - which opens to our deck - the kittens are a threat to leave. One has, a couple of times, and fortunately does not go far and we can retrieve him. We live in a suburban area and have 2 large owls in our backyard and 2 hawks nearby. In our metro area, coyotes are not unheard of. I want these kitties to be indoor cats. Does anyone have a method of keeping cats from exiting through a doggy door?