It's not unusual for a cat to stop using a litter box. It's a heads-up to their families that something is bothering them. Here are a few common litter box problems and suggestions on how to solve them. Cats may be avoiding their litter boxes for more than one reason, so you may need to try more than one thing in order to fix the problem.
What's there to fear from a litter box, you ask? Cats are quirky little creatures. They might not like:
Litter boxes might seem like insurmountable obstacles to cats if they are experiencing any pain (such as from arthritis) or medical issues (like constipation, for instance). First, they have to get to the litter box... then climb over the sides and in... then do their business in a confined space. Eliminating outside the litter box or elsewhere in the house may be less painful and easier for them.
Dementia is another example of a medical reason why cats may sometimes stop using their litter boxes.
Some medical issues can cause cats to need to urinate more frequently. If this is the case for your cat, be sure to also clean the litter box more frequently as well. Litter box liners can make this job faster and easier.
Cats don't always like the texture of a specific type of litter under their paws. If they don't like the type of litter in the box, they just might decide to forego the box in favour of something they like better, like the soft new rug in the bedroom.
Change the litter. You might consider putting out a couple of extra litter boxes, and fill each box with a different type of litter. It might take several tries to find one that your cat will accept (and one that you can live with - the clumping and odour-control capabilities, and how much the litter tracks, can vary noticeably).
There are lots of different types of litter available, made from eco-friendlier options that also provide reasonable odour-control. For example, Swheat Scoop is made from wheat; the World's Best Cat Litter is made from corn; the Next Gen Pet Green Tea Leaves Cat Litter is made from green tea powder and recycled wood; Fresh News is made from paper, and there are other types of natural cat litters as well. Use unscented litter where possible. A cat's sense of smell is far superior to our own, and added scents can be off-putting.
One thing to note is that lighter, finer litters tend to track more. Because they're lighter, they're also easier to kick around while the cat is doing its thing. Use a litter mat to help minimize the tracking of litter all over the house.
The Controversy Over Clay Litter
Clay litters, although the cheapest and most readily available, aren't the healthiest for either you or your cat. The dust that's kicked up when the cat uses the litter box or when the box is cleaned, is easily inhaled and isn't healthy for either us or our cats (many clay litters contain silica, a known carcinogen). Clay litters, once exposed to liquids, form an insoluble mass - cats that groom themselves also groom off these clumps of litter. Kittens sometimes consume litter when they're first introduced to it as well. These clumps of litter can cause uncomfortable digestive upset and may even lead to intestinal blockage. This can also affect dogs who may be attracted to "kitty box nuggets".
Clay litter is also environmentally-unfriendly; it is strip-mined and the product is non-biodegradable. That means all those litter box clumps will be here forever!
Natural cat litters are more eco-friendly and can often be flushed down the toilet, or even composted. However, the downside is the cost. They are more expensive upfront... that said, the change time between refreshing the entire litter box is often extended, so the cost per month can end up being close to the same as using clay litter.
Cats sometimes decide that they don't like the litter box itself. People often buy the covered litter boxes because it helps to keep the mess out-of-sight. The problem is that the odour can be more concentrated in the box - something that a cat, with its sensitive sense of smell, may not appreciate. Many cats also like to keep watch over their surroundings and covered litter boxes don't let them do that.
Similarly, a cat might find an automated self-cleaning litter box disconcerting if it's noisy. Another example of a 'wrong' litter box is one that's too small for the cat to use comfortably.
Try a different type of litter box, or a different size. Sometimes, simpler is better; a basic, inexpensive, open-top litter box might be just what your cat needs. There are also boxes with higher sides, and manual and automated self-cleaning litter boxes. If you suspect that your cat's current litter box might be too small, try a jumbo-sized litter box instead.
Want to keep the box out-of-sight? Place the box in a quiet room that doesn't get a lot of foot traffic, and install a cat door. The room door can then be kept closed but the cat can access his box whenever he needs to.
Sometimes cats will be attracted to an area that was previously soiled (either by himself, or by another pet). As much as the area has been cleaned, there may still be a lingering odour that's undetectable to us humans but perfectly detectable to the sensitive feline nose.
Cats might also have developed a preference for certain spots. For example, he might tend to eliminate in a dark corner, or on carpet.
In general, place litter boxes:
To discourage your cat from eliminating in a specific area:
We don't like to be dirty. Neither does a cat. Enough said.
A visit to the vet is in order if your previously litter-trained cat suddenly starts to eliminate inappropriately. It just might be that a medical issue is the underlying cause.
Sometimes the simplest change is all that's needed. Try the easy stuff first - add a new litter box in a new location (make sure to leave the regular box in its current location), or change the type of box (from open-top to closed, or vice versa, or choose a box with a lower entry wall, etc). Put 1 to 2 inches of your cat's preferred litter in the box and keep it clean.
Although not every issue can be completely fixed, most litter box problems can be resolved or at least improved.
"Cats can work out mathematically the exact place to sit that will cause most inconvenience."