Why are my cats peeing and pooping in areas that are not the litter box? Is this a territorial thing?

Normal cats (ones that are healthy, and were litter trained by their mothers) like to use their litter box and be clean. When cats experience stress, they will often act in (what seems to us) strange ways. This might include peeing and pooping in areas that are not the litter box.

Cats experience stress for many reasons. Some physical reasons that your cat may not be using their litter box include: Physical pain (ex. arthritis or having been declawed),  illness (ex. diabetes or kidney disease) and mental confusion (dementia or a recent change to the home). When your cat has been using the litter box properly and begins to ‘go’ in areas of the house that they shouldn’t, you should visit a vet to rule out the possibility of a physical cause.

Also, whether a cat has been ‘fixed’ (spayed or neutered) can affect the desire for your cat to pee in areas of the house. Unfixed males and even females are much more likely to urinate or spray to mark territory or signal sexual availability. https://pets.thenest.com/spaying-cat-keep-her-urinating-everywhere-8423.html

Cats are territorial by nature and need to feel secure in their living area in order to relax. Some cats experience stress when they have no companions/playmates. Other cats get extremely upset when they have to share the house with even one other cat.

Cats are both predator and prey and as such, can be highly excitable. If cats get bored, they can start to make their own fun. This might might include bullying another cat in the house.

Cats need to feel secure and comfortable in their home. If they do not, problems will occur and feline stress often escalates to refusing to use the litter box. This is usually the worst thing that a cat can do in your home (as far as humans are concerned) because cat urine is so difficult to clean without using an enzyme based product that is specially designed to neutralize and destroy cat urine odor.