Most cats understand how to use a litter box from the time they are kittens, as they prefer to eliminate in materials such as soil, dirt or litter. Therefore, when cats suddenly stop using their litter boxes, something more serious may be going on.
According to VCA Animal Hospitals, the sudden onset of inappropriate urination is typically caused by medical or behavioral problems. While a sick cat may eliminate inappropriately due to a number of illnesses such as bladder stones, kidney problems or related to pain, for many cats the problem is behavioral.
Cats take pride in being neat and clean, and if owners stray from keeping its litter box in tip-top shape, they sometimes start to rebel, opting to eliminate elsewhere rather than in the dirty litter. A recent switch in litter brands could also cause the rejection, possibly because the feline doesn't like the smell or texture of it.
VCA reports cats may demonstrate anxiety by avoiding the litter box. Seemingly harmless changes or situations may be very stressful for cats. For example, a new cat introduced into a household or an outdoor cat looking at an indoor cat through the window are all possible sources of stress and anxiety for a cat. If furniture is changed in the room with the litterbox or other changes are made in this room, cats often show their displeasure by eliminating outside the litterbox.
If the problem is sudden, owners should bring their felines to a veterinarian clinic first, to rule out medical conditions that may be causing the undesired behavior. If it is determined to be a behavioral disorder, an owner may want to try switching back to an old litter or cleaning the litterbox more often or making other changes to decrease the stress in the household.