I have two cats, and they are strictly indoor cats since they were kittens. I know that it would be ideal to let them go outside-inside as they wish, but I just don't have the right conditions for that. I don't think that it bothers them that they are inside. They have room to run around, furniture to climb and concur and toys to hunt down. They also have a clean toilet, fresh food and water served to them, warm temperature in the winter and cooler temperature in the summer. I live in a building, and right in front of the building is a parking lot and a playground for children. There would be a lot for me to worry about if I wanted to let them outside; people in the building, people outside, children and parents, cars, stray cats and dogs...
So I just like to keep it on the safe side.
