Why Cats Poop in the House, Not in Their Litter Box
There are several reasons why a cat might defecate in a place other than their litter box. Sadly many owners deal with this by putting the cat outside. If your cat is messing in the house it needs your attention to fix the problem. Putting the cat outside is not helping your cat.
To note it is more common for cats to urinate around the house than to defecate.
Litter Box Issues
Sometimes people use litter the cat does not like, they do not keep the litter clean, use the wrong litter box, or keep the litter box in a bad location.
If you have suddenly changed the type of litter you use that could be a major factor. Switching back to the kind the cat preferred is a good idea but it may take a while to convince the cat to use the box again.
Most cats prefer non-scented clumping litter, it is the softest, most natural litter. Some cats do not like the smell of scented litter.
Speaking of smell, most cats do not like having a dirty litter box and will “go” some place else if their box is not cleaned often enough. People who have multiple cats or who do not like to clean the litter box daily may find that having 2 or 3 litter boxes to be a good solution (ideally at least one per cat).
Some cats do not like covered boxes, some do not like open boxes, some are terrified of automatic litter boxes. Some cats need bit boxes with higher edges. If your cat is defecating near the box the problem is most likely with the style of box.
Placement of the litter box should be considered. When a litter box is near a washing machine, and if the machine changes cycle while the cat is using the litter box, it might frighten the cat, and scare it off.
Declawing sometimes changes a cat's behavior – not necessarily at once, but often later in life. Cats may start defecating all over the house as the result of a surgery done years earlier.
Most people are familiar with anal gland issues in dogs. A dog will scoot around on its rump when its anal glands become full. These are glands on either side of the anus, and cats have them too. Normally the anal glands empty every time the pet defecates, but if they have had some tummy trouble, or are getting older, sometimes this does not happen, and the anal glands become full, blocked. To correct the problem (unless you know what to do) the cat should be taken to the veterinarian, or groomer, who can express the glands, and can show you how to do it too.
Once the anal glands are empty the problem usually clears up, however the cat may need to have its anal glands expressed manually on a regular (monthly) basis after that to prevent future problems.
Some cats, to show displeasure with a change in the home, will defecate outside their litter box. You may find that paying extra attention to the cat is enough to calm it, as well try to reduce any stress the cat may be feeling. Abused cats will often poop (and pee) in the house due to the stress they feel.
Some cats, particularly tailless Manx cats, have a deformity in their rectum making it very difficult for them to control and regulate when they pass feces.
It would be such a shame to punish a cat, by putting it outside or getting rid of it, if the problem is one that can be easily solved.