I agree with LSC. We have two cats and when we got the second one she wanted to "rule the roost". We had covered litter boxes. (I have leared better.) Fifi would wait for Lamoni to get into the litter box. She would jump on top of the box and then bat at the front door to make sure that he was all the way in. Then she would pee as hard as she could down through the filter in the top of the box.

OK, shorten the story here. Lamoni took to marking and he had never done that. We went through lots of things. Wound up with one litter box in the garage and one by the back door.

I know that we should have three but we don't have room in the house due to remodling. I know the fomula: CB=NC+1 where CB is the number of cat boxes and NC is the number of cats. So that would be one box per cat plus one. One cat, two boxes. Two cats, three boxes. And so on.

By The Way: Cats HATE change. Has there been any changes in the cats environment or the household schedule? This can trigger it.

Best of luck Jesse.