Kitten stopped using litter tray after having had diarrhea

Question

TL;DR at bottom.

I've bought a new kitten 2 weeks ago. I had her confined to a room the first few days, with litter box and food/water. After a few days, I've let her roam the whole apartment, and moved the litter box to a new location (where my other cat's litter box is). That didn't seem to bother her, and she used it regularly.

Now, she has had diarrhea for the past 2 days, and while still using her box, she also started pooping at places other than her litter box (on the bed, bathroom, etc.) At first I thought it was because of the diarrhea and that she just didn't have the time to go to the box. However, earlier I was observing her, and saw her jump down from the cat tree, walk into the bathroom and take a poop there on the floor. So she is doing it intentionally. Also, her diarrhea is better and while still a bit soft, her stool has a "form" again, rather than just being a puddle.

Why is that? Why is she suddenly not using her litter box anymore? I didn't change anything in the last few days, so I'm quite confused. The only thing that comes to mind → I've used some lightly scented (aloe vera scented) wet wipes, to clean her litter box, as she got poop all over it while having diarrhea. I'm pretty sure she used the litter box once or twice, even after I've cleaned.

Some information about the litter box.

It's a closed litter box with a swing door. It's quite big, she definitely has enough room in it. I clean it daily. I use pellets made from plants. She also has access to the other cat's litter box, which uses a fine grain litter also made from plants (I think it's corn). She sometimes used it in the past. My apartment isn't huge, so the litter boxes are next to the washing machine/tumbler. That being said, I've never seen her be particularly scared of the noise they made, and they might run at most 1 time a day.

TL;DR: New kitten suddenly stopped using litter box since having had diarrhea. Her stool is back to normal, but she still is not using the litter box, and intentionally goes somewhere else to poop.

Any help is appreciated.

Answer 1

This answer is part of Pet's Spring Cleaning Campaign. This question is old, but this answer will still help people with the same problem.

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It is possible for an animal to stop liking things they were okay with in short time, especially if they aren't feeling well.

Animals think in simple categories like good (pleasant, tasty, comfortable) and bad (painful, disappointing, stressful).

Cats are inherently clean animals and like to bury their feces. Litter boxes give them to opportunity to act according to their instincts. That makes poop in litter box = good.

However, if the cat feels pain or is very uncomfortable while defecating or urinating, it may draw new conclusions:
pooping = painful = bad
pooping is done in the litter box
pooping = bad makes litterbox = bad

The same phenomenon is often observed in cats with a UTI or kidney stones that cause pain while urinating. They start peeing outside of the litter box because they connect the litter box with the pain.

One method to reset the behavior is to change the objects that are associated with bad feelings. A different litter box, maybe even with a different type of litter is worth a try, because this particular litter box isn't associated with the painful experience.

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Apart from that, cats are rather sensible in regards to chemicals. The wet wipes could have put her off, especially if they contain any citrus scent