Although most cats bury their waste, not all cats do. In most cases, cats that live with humans and use litter boxes tend to cover up their waste. The introduction of a new cat in the household, a change in your cat's health, or a change in the daily routine may cause her to stop covering her waste.

Cats learn to cover their waste when they are very young, by copying their mother. Some kittens that have been separated from their mother at a very young age may lack this learning and may take longer to learn to use the litter box.

Other times, the type of cat litter may influence the desire to dig. Larger particles may be rough and harder on paws, so the cat stops digging. The smaller particles of clumping-type litter, or a lighter-weight material might prompt better digging habits.