Why has my senior cat stopped using her litter box?

Original Question: My 15 year-old-cat is peeing, squatting inside the litter box, but her rear end hangs outside of it. Because of that, she always ends up peeing outside her litter box. What can I do to modify this behaviour? - Noemie

Jul 21, 2018

Hi Noemie,

Thanks for your question. I think it’s a great one.

I believe I know why this could be happening. When cats do this it is often because they have difficulty stepping into the litter box. Here are possibilities:

As a senior cat not using the litter box, she may have lost muscle mass in her hind legs (which can occur with hyperthyroidism, renal disease, age, arthritis, and other medical issues) and this weakness means she won’t get her backend into the box.
She is overweight and too large for the size of the litter box.
She has arthritis or back pain and it is too painful to step into the litter box.

In all of these cases, I would recommend that you create your own storage bin litter box with a low wall around it and a large surface area. You could buy a plastic storage bin and cut down the sides to a height of an inch, put it in a plastic bag so it is waterproof and sprinkle litter on it. If this is a lot of work you could find an appropriate box in a pet supply store with a similar concept.

My strong recommendation as well is to visit your veterinarian for a physical exam and consultation. There could be a disease state contributing to the problem and causing the legs to be either weak, painful, deteriorating in muscle mass or other concerning medical issues.