I have had my cat 6 years and my rabbit 5. My cat has gone into my rabbit's enclosure a few times (we always take her out immediately), but the past few days she has suddenly started using the rabbit's box to pee. Her litter box is clean, I use different litter and cover the rabbit's litter box with straw. Any ideas on why this is happening and how to stop it?
There are some possible causes and most of them have to do with the comfort of the cat. The rabbits litter may be more comfortable to use for the cat.
- The litter material: some cats have sensitive paws and dislike walking on rough surfaces. The straw that covers the rabbits litter box is soft. Maybe try a finer grained cat litter.
- The height of the litter box: especially cats with arthritis and other medical conditions concerning the joints may experience pain when climbing into their litter box. As a result they avoid peeing as long as possible (which is a risk for their kidneys) or they start peeing in other places. If your litter box has a high edge, either try a lower box or build a ramp or step to it.
- The litter box cover: Some boxes come with a cover to reduce the amount of litter that's spread in the vicinity. Some cats dislike walking into such an enclosed space because they cannot see their surroundings anymore. If your litter box has a cover, try removing it for a while.
And lastly there's always the risk that your cat has some UTI (urinary tract infection) or kidney stones. Those generally cause pain while peeing. The cat mentally connects the pain with peeing and the act of peeing with the litter box. When the cat tries to avoid the pain, it cannot avoid peeing in general, but it can avoid the litter box. So peeing in inappropriate places can be a symptom of an UTI.
To add one more possibility: If the cat considers the rabbit part of its family, sharing the litterbox may make perfect sense in feline terms. ("This thing needs my scent too", perhaps; my cat needs to rub herself on washclothes for some reason like that.) If it isn't bothering the rabbit, I'd suggest not worrying about it. If it does bother the rabbit, this is going to be a challenge.