How to solve feline house soiling

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How to solve feline house soiling
Posted on November 22, 2016 in Caring for your pet, News, Tips & Advice
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Cats want to do the right thing when it comes to the litter box, but sometimes disease or their environment overrides the instinct. Here’s how to help.

If a cat eliminates outside of its litter box, whether it is right next to the box or elsewhere, it is called house soiling. The most common causes are a medical problem and stress, which is why cats that house soil need veterinary care.

Encourage a confession

Many cat owners don’t let their veterinarians know about house soiling behaviors. They may be embarrassed or they think that it is normal for their cats or that veterinary professionals can’t help.

Owners also may not tell us because they think their cats soiled outside the box to spite them. In one large survey, 66% of cat owners thought their cat acted out of spite.1

Cats, of course, are not spiteful and instead may eliminate outside the box because of stress associated with such things as a new cat moving in or because the box wasn’t cleaned while the owner was gone all weekend.

Since many owners don’t mention the problem, it’s important to ask at each appointment if the cat has ever eliminated outside the box. It is also important to let owners know to contact you if their cats eliminate outside the box even once.

Remember the four basic causes of house soiling

Identifying the cause of house soiling is like solving a mystery. It can be overwhelming if the plan is not broken down into the four basic causes:

  • Medical causes
  • Feline idiopathic cystitis, which has been shown to be associated with stress
  • Marking such as spraying
  • Environmental or social factors

However, a cat may have two or more problems at the same time, such as the cat that sprays but also has calculi or bladder stones. So medical history and diagnostics should always be performed first. Then rule out the other problems one by one.

Help pinpoint medical causes

The most common cause of house soiling is an underlying medical problem. The cat may still be using the litter box some or most of the time. A veterinary appointment to gather a thorough history and perform an examination and diagnostic testing are essential to identify the cause. Diagnostic tests may vary based on the cat’s age and whether urine or stool or both are deposited outside the litter box.

As a veterinarian certified in feline practice and behaviorist, I routinely see cats for behavior consultations. The diagnostic testing may not be complete so that underlying medical problems are still detected—for example, a cat that sprayed urine with blood found to have bladder stones ultrasonographically that radiography did not detect, or an older cat having hyperthyroidism causing fecal soiling. A thorough medical workup is always indicated.

Create the ultimate litter box experience!

House soiling issues are often related to the litter box itself. We need to consider how many boxes are needed, their locations, their size, the appropriate litter and the frequency of cleaning.

Number. The more cats in a household, the more litter boxes needed. The rule of thumb is one litter box per cat plus one. For example, three boxes are generally needed if there are two cats in the household.

Location. It must be understood that having multiple boxes next to each other is like one box for the cats. Cats want a private and quiet area to eliminate, without competing with other cats to get to it. Boxes should be out of view from other boxes and easily accessible so that a more-timid cat does not need to pass by or get blocked by what it considers a bully cat to get to a box.

Size. Boxes should be about 1.5 times the size of the cat—from the tip of the nose to the base of the tail—to allow the cat to enter, turn around, scratch and eliminate.

Litter type. Most cats prefer sand or soil litter as they would use in the wild. Unscented clumping sand litter is an excellent option to keep boxes easier to clean for owners and desirable for cats. Many cats do not like box liners or covers, but a shy cat may prefer a covered box.

Cleaning. Litter boxes should be scooped a minimum of once daily. A box with nonclumping litter in which urine balls cannot be scooped out daily should be changed completely every week. Boxes that contain clumping litter may need cleaning only every four weeks, but it depends on the number of cats using the boxes, if boxes are cleaned daily, and whether there is more than normal urine or stool in the box due to an underlying medical problem.

Disengage marking triggers

House soiling may be cause by the cat trying to mark its territory. If the cat is not spayed or neutered, that is the first step to remove marking triggers. However, even neutered cats may spray because of the presence of other cats, whether they are outside cats looking in onto an indoor cat’s territory or a cat within the home that it does not like. Giving the cat a safe territory away from cats that it is not bonded with is very helpful. Removing the scent of marking and adding pheromones to the environment are important as well.

More resources

AAFP Practitioners and ISFM Guidelines for Diagnosing and Solving House-Soiling Behavior in Cats (includes a customizable questionnaire):
AAFP’s cat owner brochures on feline house soiling:


1. Kass PH, New JC Jr, Scarlett JM, et al. Understanding animal companion surplus in the United States: relinquishment of non-adoptables to animal shelters for euthanasia. J Appl Anim Welfare Sci 2001;4:237-248.

Ilona Rodan, DVM, DABVP (feline), is an expert in feline medicine, behavior consultant and an associate at Cat Care Clinic in Madison, Wisconsin. She is co-chair of the American Association of Feline Practitioners’ Cat Friendly Practice Committee.

The American Association of Feline Practitioners created the Cat Friendly Practice program, which provides clinics with the tools to integrate a feline perspective in both the physical environment of the practice and the way medical care is delivered. It equips practices with the tools, resources and information to elevate the treatment, handling and overall healthcare of cats, as well as emphasizes ways to reduce the stress associated with the visit. To learn more, visit

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