How to teach cats to use only the litter boxes?

Question

My girlfriend recently got 2 cats (sisters from the same litter) from an animal shelter.
They are 3 years old.

At end of May we went on vacation, and on our return we discovered to our dismay that they started peeing on her bed regularly (there were several stains).
Since then, the bedroom is not accessible to them.

A couple of weeks ago we bought a tunnel with a resting "pillow" attached to it. 3 days later we found pee on the pillow.

In the intervening time period, despite being a sofa with a surface that would absorb the pee available to them, they never pee-ed outside of the litter boxes (they have 3, we clear them twice a day).
Also, they passed their yearly visit with the vet just before she got them.
The diet has not changed, we are giving them the same food the shelter was providing, as suggested by the volunteers at the shelter.

As my girlfriend and I are thinking about moving in together, we are worrying that the cats will pee on even more furniture that has a similar texture to the pillow and the cover that was on the bed.

Are there methods to dissuade them from peeing outside the litter boxes?

Answer 1

Passing a general wellness exam in the past doesn't indicate that a cat is free of a Urinary Tract Infection (UTI) or Urinary Crystals now (or even at the time of the exam). The starting point in any case of inappropriate elimination in cats should always be a vet visit. Urination on soft surfaces is most frequently caused by discomfort when urinating (UTI or crystals), which they try to alleviate through the soft surfaces. Only your vet can rule out a UTI or crystals, and only through a urinalysis, which typically is not done on a basic checkup. Urinalysis is an added cost and procedure, and is generally reserved for cases when it's needed, rather than done as a standard procedure.

In addition, you need to thoroughly clean all the surfaces on which the cats have previously urinated, or even when they are clear of the UTI/crystal symptoms, they will continue to associate them with appropriate toileting areas due to the smell. Standard cleaning supplies do not break down cat urine sufficiently; while it may smell and feel clean to you, it's likely they'll still be able to detect the odor. You'll need an enzymatic cleaner (Nature's Miracle is a common brand), and you'll likely want a small UV flashlight to identify and target the areas that need cleaning. You can handle anything that can be laundered by using enzymatic laundry additives; everything else should be thoroughly hand-cleaned and checked with the light to ensure all traces of urine are gone.

Above all, do not punish the cats for their behavior. They are most likely not feeling well, and punishing them for doing their best to feel better will cause them to not trust you or your girlfriend, and may provoke behavioral litterbox problems, which are much harder to address than medical problems. Treat them with kindness and love, just like you'd like to receive if you were sick.

Answer 2

Any significant change in behavior can signal health issues (e.g. UTI or crystals), so I agree with @AllisonC you should rule that out with the vet first.

However, given the exact circumstances, it also seems likely that the cats were just upset about your girlfriend going on vacation and, I assume, leaving them for several days either alone or with a sitter to take care of them. Since getting the cats was "recent" and adult cats do not usually deal well with change, they may have thought they were being abandoned again, and her bed specifically would smell most like her and thus be the most attraftive place to vent their anger at her. This would explain why they have left the couch alone since she returned. The tunnel is harder to explain, but a strange new smell in the house may have set them off for some related or unrelated reason.