There aren't any particular regulations for cats, other than having to clear with your landlord or real-estage agent whether you are allowed to have pets.
Particularly outside the big cities, cats are often roaming free and most owners will have a cat flap for them to go out and come back in at their leisure. Note that
- if there isn't a cat flap already and you decide to put one in, you will most probably have to restore the door or window to its original state when you move out. This might involve replacing the door or window, or sealing the opening off.