bowel movements on floor

Question
I have 3 senior cats and starting a week ago one of them began
pooping on our stairs. We separated them to find out which one
was doing it. She is 11 years old, fixed and has never pooped  here
before.  When we gated her out of the area she didn't poop
anywhere else but the moment we opened that area she did it again  
and would almost wait until we were asleep to do it. We have began
keeping a watch on the food,water and boxes but nothing has
changed. We are fed up and think it's an attitude and not an illness
because of her not doing it any where else. She is also not acting
strange in any other manner. She still wants loving and eats fine .
Whats' going on.

Answer
Hello Ali!

Have you tried cleaning the area with an enzyme-based cleaner?  This will clean it down to the bacterial level, so she won't be able to tell she's "gone" there before.  Perhaps she accidentally went there once, and now that it smells like her (though you've cleaned it with other cleaners, there still be a bacterial trace that she will be able to detect), she will think she's okay to "go" there.  Does that make sense?

Have you had her checked out by a vet to be sure it's not a health issue?  (Not all health issues cause kitties to go in multiple places.)  I would recommend that kitties over the age of ten should be taken in at least once a year, and anytime there is any sort of personality or behavioural change, to be sure their health is still going well.  Things can go downhill so fast with senior-aged cats, they'll have a much better chance if things get handled quickly.

So, let me know about those things, ok?

Until then, hugs to you guys!

Rosie*