Understainding Behavior

The Litterbox Blues

Column Editor
Sharon L. Crowell-Davis, DVM,PhD,DACVB
Department of Anatomy and Radiology
College of Veterinary Medicine The University of Georgia
Submissions can be sent to
Beth Thompson, VMD, via email
mail Veterinary Learning Systems
780Township Line Road
or fax 800-556-3288.
About This Column
Behavior problems are a significant cause of death (euthanasia) in companion animals. While most veterinary practices are necessarily geared toward the medical aspect of care, there-are many opportunities to bring behavior awareness into the-clinic for the benefit of the pet, the owner, and ourselves. This column acknowledges the importance of behavior as part of veterinary medicine and speaks practically about using it effectively in daily practice.
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Although many people take their cat's litterbox use for granted, the feral and wild ancestors of today's cats did not eliminate in a plastic box filled with an artificial substrate in a location chosen by humans. Most housecats eliminate in a litterbox simply because of their predilection for burying their excrement. However, elimination outside the litterbox is one of the most common complaints of cat owners regarding their pet's behavior. There are two major categories of feline elimination behavior problems:

• Failure to use the litterbox

• Marking

Cats that do not use the litterbox may urinate, defecate, or do both in inappropriate areas. These cats typically void large volumes of urine on horizontal surfaces. To mark, cats usually use urine, especially in the form of spraying, which involves backing up to a vertical surface and either sticking the tail straight up in the air and twitching the end or arching the tail into a fishhook shape and urinating on the surface. On occasion, cats mark with urine by partially squatting and depositing a small amount of urine on a low vertical surface such as the bottom of a curtain or the baseboards. Less commonly, cats mark with feces, leaving them uncovered in an obvious location. Feral cats also do this on the periphery of their home range.


Failure to use the litterbox occurs for a variety of reasons that can generally be grouped into two categories:

• The cat has found something undesirable about the litterbox.
• The cat has learned to avoid the litterbox because of an unpleasant experience.

Litterboxes can be undesirable to cats for a variety of reasons, especially uncleanli-ness. It is very important for owners to keep litterboxes clean. Although many cats tolerate chronically soiled litterboxes, many others avoid them. Cats do not appear to want to use a soiled litterbox any more than humans would want to use a soiled toilet. Litterboxes should be checked at least twice daily and scooped out if they have been soiled. Nonclumping litter should be changed at least twice weekly, and clumping litter should be changed at least once monthly and more often if the owners cannot remove the small clumps that accumulate over time. The litterbox should be washed with water alone or water and a mild soap. Strong detergents and disinfectants can leave odors that are aversive to cats.
Litterboxes must be large enough for a cat to comfortably move within. When outdoors, cats move extensively as they select an area in which to eliminate, dig a hole, sniff, and cover their excrement. Many commercial litterboxes are too small for adult cats, especially if the cat is large or overweight. In general, the litterbox should be at least one and a half times the length of the cat from the tip of its nose to the base of its tail. If the largest commercial litterboxes are insufficient, a large plastic storage box with low sides may be the solution.
Lighting is critical for consistent litterbox use. Although cats have much better vision in dim light than do humans, cats cannot see in total darkness. If a cat is eliminating outside the litterbox only at night, clinicians should ask clients about the nighttime lighting in the litterbox area. If the litterbox is in a windowless, interior space with no artificial lighting and the cat is inappropriately eliminating in a section of the house with dim light, the addition of a nightlight or other artificial lighting to the litterbox area may solve the problem.
Covered litterboxes present a special problem. Feral cats do not enter caves to eliminate, and some domestic cats are not inclined to enter covered litterboxes. Although cat owners purchase covered litterboxes to hide the sight and smell of excrement, the best way to do this is to keep the litterbox clean. Nevertheless, the use of covered litterboxes may be appropriate in certain situations, such as to deter a dog with coprophagia that bothers the cat during defecation. If the room with the litterbox cannot be blocked off with a baby gate, a litterbox cover may be the best solution. Owners living in small apartments with little space for a litterbox may want to reduce the unsightliness of the litter by using a cover. If a litterbox cover is necessary, the owner should remove it at least twice daily to check and scoop out the litterbox. If this is not done, the odors can become concentrated under the cover, which a cat is likely to find highly aversive. Another problem with conventional litterbox covers is that cats using the litterbox may be attacked and trapped inside by other pets. In a multipet household, a second entrance should be cut in all litterbox covers.
Litterbox location is important as well. One cat was using the litterbox sporadically until it was discovered that the cat would not use the litterbox when the dryer, which was adjacent and loud, was running. The area where the litterbox is located should be evaluated for undesirable features (e.g., noisy, drafty, high "traffic"). The litterbox should be kept reasonably close to where the cat spends most of its time. If the cat lives in a very large house (e.g., >5,000 square feet) and the litterbox is not easily accessible, the cat may eliminate in an area where it spends most of its time.
Special litterboxes may be necessary for very young and old cats. A geriatric cat may decrease its litterbox use because of medical problems (e.g., arthritis) that make getting in and out of the litterbox uncomfortable or painful. In this case, owners should either provide a litterbox with low sides or, if higher sides are necessary, cut an entrance that the cat can step through. A mat at the entrance can help catch litter.

The 13 Rules of Treating Elimination Outside the Litterbox

1. Keep the litterbox clean.
2. Use a litterbox that is at least one and a half times the length of the cat from the tip of its nose to the base of its tail.
3. Avoid covered litterboxes, if possible. If a cover must be used and there are multiple pets in the household, cut a second entrance in the cover.
4. Avoid having the litterbox in noisy, drafty, high-traffic, or otherwise undesirable areas.
5. Provide at least dim light during the night.
6. If the cat is very young, old, or disabled, cut a low entrance into the litterbox.
7. If the cat does not dig in the litter and cover its excrement, simultaneously offer two or more kinds of litter in separate litterboxes and keep a log of the cat's preferences. A number of different litters may need to be tried before the owner can identify one that the cat prefers.
8. If there is a suspected history of learned aversion, offer the cat a new litterbox in a new location.
9. If there are multiple cats in the house, provide as many litterboxes as there are cats, plus one more litterbox.
10. Place the litterboxes in multiple sites.
11. if there is a social conflict between any of the cats, address the conflict.
12. If the cat has long hair, trim the excess hair between the digits and around the perineum.
13. If anxiety is suspected, treat the cat with anxiolytics (Table 1).

Table 1. Medications Commonly Used to Treat Urine Marking and Litterbox Aversion in Cats
Generic Drug Oral Dose



Fluoxetine 0.5-1.5mg/kgq24h 0.5-1.5mg/kgq24h

Tricyclic antidepressant



0.25-1.3 mg/lcg q24h 0.5-1 mg/kg q!2h
"Because the onset of action of these drugs is slow, each should be given for a full month before the clinician assesses whether it is beneficial to the patient. These drugs may be given in combination with benzodiazepines.

Litter preference is also a major issue. Every cat can have unique preferences for particular substrate textures and odors for burying excrement. If the cat does not dig a hole, does not cover its excrement, stands with one or more paws on the edge of the litterbox, and/or shakes its paws as it exits the litterbox, the cat likely finds something about the litter aversive. In this case, the cat should simultaneously be offered multiple types of litter, preferably side by side in identical boxes. The owner should keep a record of the cat's litter use and may need to try a number of litters before finding one the cat likes. Some cats prefer one litter for urination and another for defecation. In a multicat household, individual cats may have different preferences, making it necessary to provide a litterbox to suit each cat's needs. Cats sometimes prefer substrates that are not marketed as litter (e.g., potting soil, baby diapers). In general, strongly scented litter should be avoided; such scents are usually added for human preference, not feline preference.

Sometimes the litterbox, litter, and site are entirely acceptable, but the cat begins avoiding the litterbox because of a learned aversion. Veterinarians should watch for a litterbox aversion that develops after surgery, especially declawing and castration, or an illness, especially gastrointestinal or urinary tract disease. If cats experience pain while eliminating in the litterbox, they may associate the litterbox with the pain and subsequently eliminate elsewhere. If the pain is chronic, a cat may continue trying multiple locations as it seeks one where it can eliminate without experiencing pain. Pain control and treatment of the illness are critical in minimizing exacerbation of the elimination problem. Once the cat is completely well and is not experiencing pain, it may still avoid the litterbox because it previously had an unpleasant experience. Providing the cat with a new litterbox in a new location and perhaps a new litter may address this problem. If this does not work, temporary use of anxiolytics may be necessary (Table 1).

Social conflict between cats or a lack of adequate litterbox sites can also lead to elimination behavior problems. In multicat households, there should ideally be as many litterboxes as there are cats, plus one more litterbox. Even if there is no social conflict, a "line at the bathroom" can result in a cat seeking an alternative site
if the one litterbox in the house is already in use when the cat needs to eliminate. If having the recommended number of litterboxes is impossible because of the number of cats and the size of the house, there should at least be multiple litterboxes. The litterboxes also need to be in multiple sites. In one household with three cats, there were three litterboxes in the same room. The dominant cat in the household spent much of the day sitting at the entrance to the room and would not allow the lowest "ranking" cat to enter. As a result, the subordinate cat eliminated in the basement. Placement of a litterbox in the basement solved the problem. Significant social conflict in the household needs to be treated as a primary problem. Serious cases of intercat aggression sometimes manifest as elimination problems because a low-ranking cat is attacked anytime it comes out of hiding and attempts to approach the litterbox. In this case, the low-ranking cat eliminates wherever it spends its time. (Intercat aggression will be addressed in detail in a future column.)

Longhaired cats sometimes have special litterbox problems, especially if they have long, dense hair between their toes that covers their digital pads. This can interfere with normal sensation of the litter and can cause litter to become trapped between the hair and toes. Longhaired cats may also experience discomfort during elimination if feces become trapped in the long hair of the perineal region. In some cases, simply trimming the interdigital and perineal hair can quickly resolve the problem.

Management of marking is based on resolution of the stress and/or anxiety problem causing the behavior. If the cat is marking because of social conflict within the household, the conflict must be resolved. If the cat is responding to outdoor cats entering the yard and approaching doors or windows, the "visitors" can be kept away with tools such as the Scarecrow (Contech) motion-activated sprinkler. Holiday seasons are very stressful for many cats because of schedule changes, visitors, and environmental changes such as decorations. Cats that mark as a result of stressors that cannot be removed often benefit from the administration of anxiolytics such as fluoxetine, paroxetine, clomipramine, or buspirone (Table 1). Feliway, an analogue of feline facial pheromones, may also be beneficial in some cases; however, in my experience, it also can occasionally exacerbate the problem.

Elimination in the artificial environment of a litterbox is not a natural behavior for cats. To prevent and treat feline elimination behavior problems, veterinarians need to understand the role of learning, individual litterbox preferences, and a cat's motivation to dig and bury its excrement. Veterinarians also need to consider the role of stress and social conflict in the development of marking problems. A cat that lives in a suitable environment and is happy with its litterbox will consistently eliminate there.