We have two older male cats (both neutered). Until recently, they both used the litter box correctly. Now on occasion, one of them, urinates and or poops just outside the box. Why would they do this and what can we do to change the behavior of stinking outside the box?

Do you clean the box regularly if not this could be the problem.

Have you changed the brand of litter? Do you actually wash the box periodically in addition to adding all new litter when you do? We have to do the washed box-new litter thing once a week or Thomas Jefferson won't use the box any longer.

Have you moved the box to a new place? Has the cat food brand been changed? Has something changed in the house or with the family? Cats don't like any kind of change.