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Feline House-soiling
Published: September 24, 2020
This cat is drawn to freshly cleaned litterboxes. Photo by Dr. Teri Ann Oursler/VIN

Elimination disorders are one of the most frustrating behaviors that cat owners encounter and a leading reason for cats to be surrendered to shelters or euthanized. Although elimination is a normal communicative behavior for cats and can serve a specific purpose, people might find the location(s) unacceptable.

When your cat is eliminating outside the box, it is important to have all potential medical causes for the behavior ruled out with a physical examination by your veterinarian and the necessary diagnostics. Once medical conditions are ruled out, elimination disorders can then be broken down into two main categories: Inappropriate elimination (toileting) or marking (spraying). A complete history including litter type, litter box size, the cleanliness of the box, and social relationship between the cats can help to determine why your cat is choosing to eliminate outside the box.

Physical exam Findings in Cats Displaying Problems

  • Penile barbs/spines
  • Abdominal pain
  • Abnormal kidneys (size and shape)
  • Palpable bladder calculi (your vet can feel the bladder stones)
  • Overgrooming in the groin
  • Palpable thyroid (your vet can feel that it is abnormal in shape) 

Common Medical Causes of Inappropriate Elimination (Toileting) 

  • Hyperthyroidism
  • Diabetes mellitus
  • Liver disease
  • Feline idiopathic cystitis (FIC)/FLUTD
  • Kidney disease
  • Arthritis

Inappropriate Elimination (Toileting)

Cleanliness of the box is often the number one reason that cats will choose other locations to eliminate. Location, litter type, litter box size, and type of box are important factors to evaluate when determining a cause. The litterbox should be scooped at least daily and the litter changed every one to two weeks. When cleaning the box, only soap and water should be used since most cats will find citrus scented products unpleasant.

Current research shows that the most important factor when choosing a box is size and not necessarily whether it is covered or not. Most commercial litter boxes are too small for the average cat and creating a litter box out of a plastic storage container or a sweater box may be a better choice. Most cats do not like automatic litter boxes or litter box liners.

Cats with an aversion to the litterbox will often avoid the box completely, fail to dig in the box, or cover their elimination. Many will straddle the box, shake their feet excessively after leaving the box, or eliminate near but not in the box. If it is a substrate aversion, they will show a preference for a particular substrate such as carpet, tile, or piece of furniture. These cats will often choose a closet or secluded area of the house and often have a medical reason that initially causes elimination to occur outside of the box although the behavior continues after the primary condition resolves.

Treatment for inappropriate elimination involves offering a variety of boxes with litter choices, including a litterbox cafeteria. Most cats prefer cheap, clumping, non-scented litter. Placing a different type of litter in each box at varying depths next to each other is a way to monitor which litter and depth each cat prefers for elimination. A rug box that consists of an empty box with a throw rug (washable soft material) is helpful for cats with a carpet or cloth substrate preference. Cats often prefer to eliminate within the confines of the box vs. out in the open, reducing elimination on the carpet.

Clean the areas where the cat has been eliminating with an enzyme-based cleaner. Injecting the cleaner into carpet pads, furniture seams, wall seams, and behind baseboards will help to clean all areas. Place deterrents in previously soiled areas, such as an upside-down carpet runner with heavily perfumed soaps spread on top for a deterrent. Change the value of the area by turning it into a feeding station or preventing access to the area altogether by using gates and closing doors.

Inappropriate Elimination (Toileting) Marking

Usually horizontal surfaces

Squatting position

Large amount of urine or feces

Eliminates near but not in the box

Vertical surfaces (walls, drapes, furniture)

Most stand but some will squat

Small amounts of urine

Will still use the box for most elimination


Marking is a common behavior found in unneutered males but can also occur in neutered males and a small percentage of spayed females. Cats often mark for two main reasons: one is to signal territory and the other to reduce anxiety. Most marking does not have an underlying medical cause and usually indicates a social anxiety among cats in the household or a view of other cats outside windows.

Treatment for marking involves identifying the underlying social tension by observing communication signals of all cats in the household. Overtly aggressive or “bully” cats will stalk, pounce, growl, and attack the victim cat. The victim cat will actively avoid the bully cat. They may leave the room as soon as the other cat enters or walk the perimeter rather than through the center of the room. You may often find this cat up high on surfaces, or hiding under the bed or behind furniture. Cats that are aroused by outdoor cats may suddenly become aggressive to other cats or people in the household after encountering another cat outside the window or door. These cats can stay in an aroused state for hours to weeks and should be carefully separated until they have time to settle down. 

When there are multiple cats in the household, make sure there are plenty of resources for all of them: litter boxes, feeding stations, vertical spaces, sleeping stations, hiding areas, and water bowls.

Punishment is often ineffective and confusing for cats who and reward-based training helps to provide mental stimulation and positive human interactions. Scheduling 20-30 minutes of playtime a day along with 5-10 minutes of positive reinforcement training time daily is ideal. Cats can be taught basic behaviors such as “sit”, “come”, “mat” and targeting or “touch.” All provide clear communication and can be used for redirection if confrontation occurs with another household cat. These behaviors, along with play, can help to change emotional responses to another cat, person, or animal in the household during the behavior modification process.

Behavioral History

  • Triggers
  • Locations
  • On what substrate?
  • Vertical vs. horizontal
  • Owner’s response
  • Elimination behavior in box (digging, time spent in box, cover feces)
  • Location of elimination
  • Box size and number
  • Cleaning habits
  • Relationship between cats
  • Environmental changes
  • Dog or other animal in the home
  • Video to show who is eliminating
  • Breed of cat

The use of food dispensing and puzzle toys add mental stimulation and enrichment by simulating hunting behavior. Outdoor access in the form of walks on a harness or in an enclosure can provide physical exercise and mental stimulation.

Cats with litter box aversions or substrate preferences do not necessarily need medications. Once the cause is identified and the hygiene of the box improved, the cat often returns to using the box. Marking in cats often responds well to serotonin enhancing medications such as fluoxetine (Prozac) and clomipramine (Clomicalm).

Pheromones can be useful in the forms of sprays and diffusers. Therapeutic diets available at your veterinary clinic may be useful. These diets contain milk protein and L-theanine which can also be found in supplements such as Zylkene (Vetoquinol), Anxitane (Virbac), and Solliquin (Nutramax), which in some studies have shown to increase calmness and relaxation.

Work with your veterinarian or a veterinary behaviorist if your cat continues to have problems with inappropriate elimination or marking indoors.

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