The Association between Feline Elimination and Feline Aggression Disorders
World Small Animal Veterinary Association World Congress Proceedings, 2005
Karen L. Overall, MA, VMD, PhD, DACVB, ABS Certified Applied Animal Behaviorist
Center for Neurobiology and Behavior, School of Medicine, Psychiatry Department, University of Pennsylvania
Philadelphia, PA, USA


Inappropriate elimination may represent 30-50% of feline behavior referrals.1 Cats who do not use their litter box-regardless of the underlying reason--are at risk for euthanasia, relinquishment, or abandonment.2-4 History is key to understanding and treating the clients concerns. Modern veterinary medicine mandates and evaluation for behavioral problems at each visit. This process will allow the practitioner to intervene and advise the clients when such attention is most efficacious: early in the development of problems.5

History and diagnosis

Patterns of elimination are important. Are there any 'rules' that the cat has for using the box, and if so, what are they (e.g., the cat always uses the box just after it is cleaned and the litter replaced)? Is the cat urinating on a horizontal or vertical surface? Often a vertical surface suggests spraying. If the cat is urinating on a horizontal surface, where is the cat eliminating? Are the areas that the cat is using linked by location or by the type of substrates chosen for elimination? Common locations include the area just outside of the box, or in a place where the cat can hide. Common substrates include clothing, bedding, certain smooth, reflective, flat surfaces in the household (e.g., porcelain surfaces, furniture, other locations on the floor). In all cases, it is essential that a medical diagnosis be eliminated before proceeding to treat any behavioral concerns. Even if there is also a concomitant medical diagnosis6, behavioral treatment is needed because the cat may have learned either to avoid the box if using it was associated with pain, or that other surfaces have an previously unappreciated appeal.1

A minimum laboratory baseline for any cat with any complaint involving elimination includes a CBC, serum biochemistry profile, urinalysis, +/- fecal (if feces are involved), and at least a lead II rhythm strip if tricyclic antidepressants or selective serotonin reuptake inhibitors will be considered as part of the treatment plan.

The most common elimination complaints that are fundamentally behavioral involve substrate or location aversions, substrate or location preferences for urination, defecation, and spraying. While spraying can be a normal feline behavior, unless hormonal stimuli are involved, it is likely to more often be a non-specific sign of social stress or distress. The scenario of social stress may be more common in households with multiple cats, all of whom are maintained indoors.

Aversions to substrates or location can be difficult to distinguish from preferences, and invariably lead to the cat choosing another location or substrate for elimination. We may never know why the cat has developed an aversion to one location or one substrate since aversions only become apparent because of the cat's total avoidance of the offending area or surface. In cases involving aversions that have developed in response to an horrific experience, some owners have reported that the animal will hiss, growl, slink, or piloerect when found in proximity to the substrate or area.

Onychectomy / declaw coupled with premature return to gravelly kitty litter has been implicated in the development of some aversions to substrate. For ultra fastidious cats, vomit or diarrhea, may induce the same response.

Pure location aversions are more often coupled to fearful or painful situations, such as injuries caused by doors or torment from another cat or a child. If a cat is absolutely avoiding a specific area or substrate for elimination, they will find another until they are presented with suitable options

Substrate preferences for elimination are extremely common, and there is anecdotal data that among long haired cats are particularly affected. When cats manifest a substrate preference they prefer some other substrate than the offered litter for elimination. Although the substrate preferred is usually softer (sheets, underwear, bath mats, plastic trash bags), this does not have to be so, and some cats prefer open, reflective areas such as linoleum, wood floors, tiles, and bathtubs. The ancestral and wild condition for elimination in felids involves open, reflective, well-drained substrates, and in the wild urine and, or feces may not be covered.

Substrate preferences can develop spontaneously or be induced. Many clients complain of the problem after an extended vacation where someone fed their cat, but would not change the litter. The cat is repulsed by the filthy litter, seeks another area from desperation, and discovers that it prefers this substrate. Illness can also be implicated in the development of a preference; a cat with cystitis or diarrhea may not be able to make it to the litter box and in the process of covering up the urine or feces on the carpet, discovers that it likes carpeting.

Most location preferences are mixed substrate / location preferences. In a true location preference, the cat prefers one or a few areas for urination or defecation; none of these is generally its litter box. These cats will often use a litter box placed in the preferred area. If so, it will be possible to move the box slowly (1-2 inches per day) to an area the client prefers, providing there are no complications involving social stress. The client should watch for relapses, which may signal a misdiagnosis. Non-spraying marking with urine can look like a location preference.

Spraying can be done by male or female, intact or neutered animals. Clients often confuse spraying with urination.7 Encourage clients to describe postures and note locations. If the cat is standing, wiggling its tail with a look of bliss on its face, it is spraying. Sprayed urine hits vertical surfaces and drips down. Cats can also stand in the middle of a horizontal surface, such as a bed, a spray, in which case they will leave a long, thin wet area, rather than a puddle. Have clients crawl on their hands and knees over every inch of carpet; if there is urine in a puddle in the middle, but no where else, the cat is not spraying. Spraying can be triggered by hormones, by the addition of a new animal, by the visitation of a strange cat to windows or sliding glass doors, by partial obstructions, by seasonal changes, and by events only understood by cats. Many cats will spray against the inside of covered boxes.

Roles for intercat aggression and other social stressors

Social stress and distress are important in the development of problematic feline elimination behaviors. Accordingly, it is essential to assess whether the primary anxiety disorder affecting cats in the same household--intercat aggression--is a concern. If the client has addressed all manifestations of the elimination problem and it still persists, the reason is likely a conflict in the household, or with an individual who visits outside the house.

When considered as a descriptor of normal feline behavior, intercat aggression is most commonly seen between toms. In most wild, feline social systems, few males mate with most of the females. The skewed sex ratio in the breeding population is induced and maintained by vigilance and aggression on the part of the males. There is an additional olfactory component of spraying and non-spraying marking that contributes to this normal, contextual aggression. Early neutering (prior to 12 months of age) decreases or prevents fighting by 90%.

The form of intercat aggression that is pathological and with which most clients are concerned is more commonly based on conflicts within social hierarchies, regardless of sex. Cats begin to become socially mature some where between 2 and 4 years of age, and at this time some cats may begin to challenge others. Problems arise when one cat will not accept lack of engagement by another cat. Responses include passive aggression (staring and posturing), active aggression, and marking. Cats that consider themselves as more equal are less likely to participate in overt aggression--expect covert aggression. Intercat aggression is extremely complex, often subtle, and under-appreciated (See Table 1 for an example of potential scenarios).

Table 1. Sample scenarios involving various modes of intercat aggression:

 Overt, passive, offensive aggression: confident cat staring when another enters room.

 Overt, passive, defensive aggression: less confident cat leaving room or backing up and withdrawing into smaller space, tail tucked vocalizing.

 Covert, passive, defensive aggression: vanquished or less confident marking with mystacial glands in boundary areas or areas from which cat had been displaced.

 Covert, active, offensive aggression: vanquished or less confident marking with urine or feces in boundary areas or areas from which cat had been displaced.

 Overt, active, offensive aggression: chase and attack using teeth and accompanied by vocalization by resident cat toward new cat in environment.

 Overt, active, defensive aggression: attack or response using hitting and or swatting while leaning back or avoiding further pursuit.

 Covert, active, defensive aggression: withdrawal and marking of restricted area by victim cat

 Covert, passive, offensive aggression: displacement or theft of "bully" or higher ranking cat's toys, bed, food, accompanied by non-elimination pheromonal marking.


When treating the behavioral aspects of problematic urination, medication may be extremely useful as an adjuvant to behavioral (Tables 2 & 3).8 Premedication physical and laboratory evaluation in cats is essential, not optional.

Benzodiazepines, while humanly abusable, can be excellent drugs for some cats who have joint elimination / aggression problems because of underlying non-specific anxiety that results in a decrease in outgoing behavior in the affected cat. Clients should be advised to watch for any signs associated with hepatopathies, although these are extraordinarily rare. The exact mechanism of action of the benzodiazepines (e.g., diazepam, chlordiazepoxide, clorazepate, lorazepam, alprazolam, and clonazepam) is poorly understood. Calming effects may be due to limbic system and reticular formation effects. Compared with barbiturates, cortical function is relatively unimpaired by benzodiazepines. All benzodiazepines potentiate the effects of GABA by increasing binding affinity of the GABA receptor for GABA. Binding of diazepam is highest in the cerebral cortex compared with the limbic system and midbrain, which are, in turn, higher than the brainstem and the spinal cord, paralleling the distribution of GABAA receptors. At low dosages, benzodiazepines act as mild sedatives, facilitating daytime activity by tempering excitement. At moderate dosages they act as anti-anxiety agents, facilitating social interaction in a more proactive manner. At high dosages they act as hypnotics, facilitating sleep. Ataxia and profound sedation usually only occur at dosages beyond those needed for anxiolytic effects. Note that the duration of action of the parent compound, diazepam, and its intermediate metabolite, nordiazepam (N-desmethyl diazepam) in cats is 5.5 h and 21 h, respectively.

Tricyclic antidepressants (TCAs) act to inhibit serotonin and norepinephrine re-uptake, and can be useful for some cats that spray, some who are averse to or anxious about their litter box, and cats who are experiencing anxiety about heir social situation. Drugs of choice include amitriptyline and its active intermediate metabolite, nortriptyline, and clomipramine.9 There are three major effects of TCAs that vary in degree depending on the individual drug: (1) sedation, (2) peripheral and central anticholinergic action, and (3) potentiation of CNS biogenic amines by blocking their re-uptake presynaptically. Knowledge of intermediate metabolites can be important: animals experiencing sedation or other side effects with the parent compound may do quite well when treated with the intermediate metabolite, alone. For example, cats that become sedated or nauseous when treated with amitriptyline may respond well when treated with nortriptyline at the same dose since the former has 2x the NE-re-uptake effect of the latter.

Partial 5-HT1A/B agonists (e.g., buspirone) have few side effects, do not negatively affect cognition, allow rehabilitation by influencing cognition, attention, arousal, and mood regulation, and may aid in treating aggression associated with impaired social interaction.

The SSRIs (fluoxetine, paroxetine, sertraline, and fluvoxamine) are derivatives of TCAs. These drugs have a long half-life, and after 2-3 weeks plasma levels peak within 4-8 hours. Since these drugs act to induce receptor conformation changes--an action that can take 3-5 weeks--treatment must continue for a minimum of 6-8 weeks before a determination about efficacy can be made. Most of the SSRI effects are due to highly selective blockade of the re-uptake of 5-HT1A into pre-synaptic neurons.

Newer treatments involving a synthetic analogue of feline cheek gland secretions (e.g, pheromones) (FeliwayTM) show some promise for spraying that either has recently started and is related to the introduction of a new individual (human or animal), or to disruptions in the colony scent. Few excellent studies have been conducted, which is problematic because the mechanism of action is unknown. In some cases the concomitant use of pheromonal agents and anti-anxiety medications may produce a quicker resolution than would be produced by either alone, but most data are anecdotal.

Table 2. Useful medications (brand names are those in the US) for the treatment of intercat aggression and concomitant elimination concerns, with algorithm for use based on mechanisms of action and side effects

1.  Diazepam (Benzodiazepine; Valium): for the victim, primarily, to make more outgoing and friendlier; for the aggressor if aggression is secondary to anxiety about interaction and increased friendliness will help.

2.  Amitriptyline (TCA; Elavil): for the victim or aggressor with non-specific anxiety.

3.  Nortriptyline (TCA; Pamelor): for the victim or aggressor with non-specific anxiety and sedation with amitriptyline.

4.  Clomipramine (TCA; Clomicalm): for the victim or aggressor with more specific anxiety.

5.  Buspirone (NSA; BuSpar): for the victim, only; may make more outgoing and situation resolves with some overt aggression.

6.  Fluoxetine, paroxetine (SSRI; Prozac, Paxil): for more specific anxieties involving outburst (fluoxetine) and social (paroxetine) anxieties.

Table 3. Dosages for medications discussed in the text

[Note: brand names are those for the USA; countries differ]

Amitriptyline (TCA; Elavil)

0.5-1.0 mg / kg po q 12-24 h; 2.5-5.0 mg/cat po q 12-24 h

Nortriptyline (TCA; Pamelor)

0.5-1.0 mg / kg po q 12-24 h; 2.5-5.0 mg/cat po q 12-24 h

Buspirone (NSA; BuSpar)

0.5-1.0 mg / kg po q 12-24 h; 5-10 mg/cat po q 12-24 h

Clomipramine (TCA; Anafranil)

0.25-0.5 mg/kg po q 24 h

Diazepam (Benzodiazepine; Valium)

0.2-0.4 mg / kg po q 12-24 h; 1-2 mg/cat po q 12-24 h

Fluoxetine (SSRI; Prozac)

0.5 mg/kg po q 24 h

Paroxetine (SSRI; Paxil)

0.5 mg/kg po q 24 h


1.  Overall KL. Diagnosing-feline elimination disorders. Vet Med 1998;93:350-363.

2.  Miller D, Staats S, Partlo C. Factors associated with the decision to surrender a pet to an animal shelter. J Am Vet Med Assoc 1996;209:738-742.

3.  New J, Salman MD, King M, et al. Characteristics of shelter-relinquished animals and their owners compared with animals and their owners in US pet-owning households. JAppl Anim Welf Sci 2000;3:179-201.

4.  Scarlett JM, Salman MD, New JG, Jr., Kass PH. Reasons for relinquishment of companion animls in US animal shelters: selected health and personal issues. J Appl Anim Welf Sci 1999;2:41-58.

5.  Overall KL, Rodan I, Beaver BV, et al. Feline Behavior Guidelines from the American Association of Feline Practitioners. American Association of Feline Practitioners, 2004, in press.

6.  Overall KL. Medical differentials with potential behavioral manifestations. Vet Clin NA: Small Animal Pract 2003;33:213-230.

7.  Bergman L, Hart BL, Bain M, Cliff K. Evaluation of urine marking by cats as a model for understanding veterinary diagnostic and treatment approaches and client attitudes. J Am Vet Med Assoc 2004, 221:1282-1286.

8.  Overall KL. Paradigms for pharmacologic use as a treatment component in feline behavioral medicine. JFMS 2004,6:29-42.

9.  King JN, Steffan J, Heath SE, et al. Determination of the dosage of clomipramine for the treatment of urine spraying in cats. J Amer Vet Med Assoc 2004,225:881-887.

Speaker Information
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Karen L. Overall, MA, VMD, PhD, DACVB, ABS Certified Applied Animal
Center for Neurobiology and Behavior, School of Medicine, University of Pennsylvania
Philadelphia, PA

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