Housesoiling is the most common behavior problem for which cat owners seek help. The typical cat's convenient, welcome habit of disposing of urine and stool in a litterbox help make it a popular indoor pet. On the other hand, the indiscriminate elimination habits of some cats have contributed to their demise. It's very frustrating for owners who have to cope with the disagreeable problem of housesoiling by an otherwise loving, wonderful pet.

Once underlying medical problems have been ruled out, the first step in working up a housesoiling problem is to find out whether the cat is spraying a vertical surface or eliminating inappropriately on horizontal surfaces. Spraying occurs when a cat backs up to an upright surface and directs a stream of urine toward it. The amount is typically smaller than what is voided when a cat empties its bladder during normal urination. This is a marking behavior that is typically caused by territorial or stressful situations.

The density of cats in the home contributes to the incidence of spraying. Spraying increases from 25% in single-cat households to 100% in households with more than ten cats. Intact males or females in heat are the individuals most likely to engage in this type of behavior, although some neutered cats will spray. In fact, studies have shown that as many as 10% of prepubertally castrated male cats and 5% of prepubertally spayed female cats take up spraying on a frequent basis as adults. Objects that are commonly sprayed include doors, walls by doors or windows, new objects in the house and furniture.

Inappropriate elimination can been defined as the act of squatting to defecate or urinate on horizontal surfaces outside the litterbox that are unacceptable to the owner. Housesoiling that occurs as a squatting behavior occurs with an almost equal incidence in females and males. There are many causes of inappropriate elimination. If the cat suddenly starts urinating and defecating outside the box, then it's highly likely that something about the litterbox is aversive to the cat. The physical accumulation of waste, organic odor, disinfectant odor, unacceptable litter or a negative experience associated with the litterbox may cause the pet to avoid it. The box may be in an area the cat does not like. There may be too much traffic through the area, or the area may be associated with something aversive that happened to the cat. Perhaps it was medicated, disciplined or frightened in the vicinity of the box. If the pet has been severely punished for any reason, it may start eliminating in secluded areas in order to avoid family members. Some cats will eliminate outside the litterbox simply because they have found another area or surface that is preferable.

If the cat consistently defecates in the box, but urinates elsewhere, or vice versa, then the problem probably isn't caused by an undesirable litterbox, substrate or box location. Likely causes are medical problems, new surface preferences or new location preferences. Other causes of inappropriate elimination include a need for privacy and medical problems (cystitis, constipation, diarrhea, diabetes, renal disease, arthritis, senility). Be suspicious of constipation or colitis if an older pet suddenly stops defecating in the litterbox, but continues to use it for urination.

In some cats, the act of eliminating on horizontal surfaces can be a marking behavior caused by the same stimuli that cause spraying. This will result in a puddle if the cat squats or a linear wet area if the cat sprays in the middle of a room or bed, but not near an upright object. As mentioned earlier, the most common cause is increased cat density. Emotional problems, such as a stressful relationship with a family member, separation anxiety or fear can trigger housesoiling. If the cat is urinating on top of specific items, such as the owner's clothing, bed or favorite chair, you will want to be sure to explore an anxiety-related problem. If emotional factors are maintaining the housesoiling, you may expect to see related changes occurring, such as hiding, avoidance, aggression or an alteration in the pet's general temperament or behavior. Keeping a diary may help the owner identify the stimuli that trigger intermittent marking episodes.