Cats have this quirk of being territorial pets. Even for siblings of the same brood, some cats usually prefer their own personal space. When cats are in the process of eliminating their feces and urine, the process can be quite private and needs to be done without sharing a litter box. In some cases, cats are known to mark their own territory by spraying urine, which applies also to the litter pan. It would be ideal to have a personalized sandbox per cat and an extra mixed-use one, for a multi-cat home.
Like siblings, an Alpha cat may bully the other siblings and block them from using the litter box. This may lead to your cats eliminating anywhere else except the sandbox. Putting your litter pans at different sides of the house may disengage blocking of entry and usage of these pans. However, your sandboxes must be located in areas acceptable for use as most cats usually have an aversion to noisy environments.
A sudden change in your pet’s elimination habits should warrant an appointment with your pet hospital Washington DC. Read more here.