Housesoiling - Cat

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House soiling is the most common behavioural problem reported by cat owners [1][2]. House soiling is an umbrella term for problems in which urine or faeces are deposited inappropriately in the home, with two sub categories of problem being inappropriate elimination and indoor marking behaviour. It is important to differentiate between these problems as they require differing types of treatment. Since they often relate to an underlying cause due to fear or anxiety, inappropriate elimination and indoor marking can occur concurrently. Underlying medical conditions must also be ruled out before a behavioural diagnosis is considered.

Medical Assessment

Medical factors are very important in housesoiling and marking problems. Medical problems can underlie and cause behavioural problems, or they can contribute to them (see table). For example, conditions causing PU/PD can cause an indoor elimination problem by increasing the urgency to urinate in a cat that has problems accessing a latrine quickly, or it can contribute to an increased frequency of indoor elimination in a cat that already has a behavioural problem.

Medical factors underlying housesoiling problems
Conditions causing PU/PD: renal insufficiency, diabetes mellitus.
Feline lower urinary tract disease.
Diseases causing debilitation: osteoarthritis, senile dementia, and sensory loss.
Diseases affecting cognition: cognitive dysfunction syndrome, CNS pathology (primary or secondary to systemic disease).

Any condition which affects gastrointestinal or urinary tract function is a potential candidate for involvement in cases of inappropriate elimination and a full medical examination is therefore essential. Any medical condition which alters the cat’s mobility or cognition may limit its ability to gain access to latrines or disrupt established elimination routines and housetraining. Organic disease may also be a factor in cases of undesirable marking behaviour.

The medical workup must include:

  • Medical history
  • Clinical examination – including abdominal palpation
  • Urinalysis
  • Assessment of mobility, cognitive function and sensory perception
  • Further investigation through haematology, biochemistry or imaging techniques, as required.


It may be difficult in some cases to differentiate between inappropriate elimination and indoor marking behaviour, and in some cases these two problems may occur together. It is important to collect all of the information needed to make a judgement:

Example of a house plan
  • Age of onset
  • Previous record of house training
  • Pattern of deposits – location, frequency, volume
  • Orientation of deposits – onto vertical or horizontal surfaces
  • Posture and behaviour of the cat during deposition
  • Relationships between animals in the household
  • Presence or absence of the owner or other animals around the time of soiling (including other cats seen outside)
  • Owner’s reaction to the deposits
  • Events in the household or the neighbourhood coinciding with the onset of the behaviour
  • Assessment of the cat’s emotional reactions to novelty in the environment and to strangers
  • Assessment of the environment: quality and location of resources, including latrine sites such as litter trays

Using a House Plan

Owners should be asked to draw a floor plan of the house, indicating when and where urine and faeces have been discovered. The owner should mark onto this diagram the location of urine and faeces that they have found, as well as the location of major resources (food and water locations, litter trays, cat doors), and the position of doors and windows (see figure). This can be annotated during the consultation with information about the cat(s) preferences for resting locations, and the frequency, volume and characteristics of deposited of urine/faeces. The client should also be asked to indicate in which locations urine/faeces was first found, and how this spread to other locations. A standard method of annotation is to mark the frequency of urine deposition using a number of "X"s, and a number to indicate whether the location was one of the first, or later, places that was soiled (see example).

The pattern of urine and faecal deposits can point to the source of the problem. For example, if the first deposits were found close to external doors and windows, this suggests that the perceived threat is from outside the home, whilst initial deposits near furniture and internal doorways and passages would suggest that the problem originates in the relationship between resident cats in a multi-cat household.

Once all of this information has been collected, it is then possible to make judgments about the nature of the problem, whether it is a matter of indoor marking or elimination and what the motivation may be.

Differentiating Between Elimination and Marking

Once full information has been collected about the location and characteristics of each urine or faecal deposit, it is possible to make a judgement about the cause.

Location and Orientation of Deposits

The type of locations used for marking are different from those used for elimination. In the case of marking, the location of marks is intended to convey a signal to other cats; the function of spray marking is to maintain temporal and spatial distance between cats. Marks are therefore left in visible locations close to points of entry to an area; for example in a doorway into a room, or at the bottom of a flight of stairs. They may also be left in places where the cat is responding to an interaction with another cat; for example, by a window or on a spot where a non-resident cat has recently been seen. The act of spraying also involves an element of visual display. When cats spray mark, urine is normally deposited onto vertical surfaces, but in some situations cats will spray onto a horizontal surface if there is no other a choice.

Inappropriate indoor elimination is not a display, and cats seek to maintain privacy whilst eliminating. Eliminated urine and faeces are therefore usually deposited in quiet secluded locations where the cat will not be disturbed. In households, common locations are quieter places like bathrooms and bedrooms. Cats usually have preferences for the kind of substrate that they will eliminate on, which may relate to their rearing environment; kittens that are reared a cage or crate may develop a preference for eliminating on bedding or newspaper because these were the first substrates they encountered. This can lead to adult preferences for urinating or defecating on carpets, sofas or bedding. When cats eliminate, they usually deposit urine onto a horizontal surface, but cats with LUTD may urinate standing up, or stand up as they urinate, leading to urine deposits on vertical surfaces or outside the litter tray.

Cats with lower urinary tract disease will often have episodes of using multiple sites to urinate around the house. It is thought that pain associated with micturition in a latrine site discourages repeated use of that location: The cat chooses a different latrine site next time. This pattern of urination is often cyclical, with cats eliminating normally for a few weeks and then displaying a bout of housesoiling in multiple locations. This fits with the waxing and waning cyclical nature of feline lower urinary tract disease. With cystitis, the volume of urine found at each site is usually small, and the urine has a strong odour.

Frequency of Deposits

Cats will usually urinate and defecate one to three times daily depending on food intake and meal timing. The frequency of elimination may be increased if the cat has a urinary tract or bowel problem. Cats will leave urine scent marks in many locations every day, typically returning to leave a fresh urine mark at each location at least daily. It would not be unusual for a cat to leave a scent mark in thirty or more locations per day.

Volume of Deposits

Cats with inappropriate elimination problems usually deposit larger volumes of urine at each site than cats with marking problems. However, cats with LUTD will only pass only small volumes of urine at each of multiple sites. As do cats with chronic diarrhoea. However, the choice of location will still fit with normal defecation.

Posture and Behaviour of the Cat

When cats spray in a location, they start by sniffing the spot (and often show a flehmen behaviour). The cat will then back up to the spot and spray urine with the tail erect. The cat often has a glazed look on its face, its tail will twitch and it will paddle with its back feet. This characteristic stance is different from urination behaviour, even when cat urinates standing up. Urine marking does not exclusively occur from a standing posture and it can be performed from a squatting position, but with tail movements, and foot paddling that differentiate this form urination.

When cats urinate, they usually do not investigate the area by sniffing, and the tail movements and foot paddling are not seen. If cats with LUTD urinate standing up, they usually adopt an uncomfortable posture, strain as they urinate and may vocalise painfully.

Indoor Marking Inappropriate Elimination
Behaviour and Posture:
  • Cat approaches and sniffs the location
  • It then turns around and reverses up to the spray site
  • Whilst spraying the cat will paddle its feet
  • The tail will twitch and vibrate
  • The cat may have a glazed and vacant look on its face
  • The location may be sniffed and investigated before elimination
  • Urine or faeces are deposited whilst the cat is in a crouched position with slight back arching
  • Abnormal postures may be seen during elimination: urination whilst standing up, or when crouched with a greatly arched or flattened back is indicative of pain or dysuria. In extreme cases, cats may cry or run away from the area where they have eliminated, as if in pain
  • Unlike marking behaviour, there is no visual ‘display’ element to normal elimination
  • Small to medium volumes of urine, perhaps with a greasy or oily appearance
  • Intense odour, often musty
  • Dries to a yellow-brown colour, with a greasy appearance and occasionally containing crystals
  • Faeces (middening) are of normal appearance
  • Relatively large volumes of normal urine or faeces
  • Usually highly visible locations, where marks will be easily noticed
  • Most often urine is placed on vertical surfaces, but occasionally horizontal
  • Urine may be placed high up on the vertical object
  • Objects that heat up and cool down may attract spray marks (heaters, toasters, TV and audio equipment)
  • Bags, shoes and other objects that may carry foreign odours into the home may be targeted
  • Faeces (middening) are deposited, unburied, in open spaces where they will be most visible
  • Unless a particular location is excessively soiled and becomes objectionable to use, the cat will tend to use only a small number of latrine sites for elimination: one for urine and one for faeces
  • Latrines are usually in quiet locations where the cat will have some privacy when eliminating

Pattern of Deposition of Urine and Faeces (identified using a house plan)

As a situation progresses, the pattern of deposition of urine and faeces can become increasingly confusing so that it becomes very difficult to identify the originating cause unless the historical development of the pattern of the marking or elimination is recorded using a house plan. If the first urine marks were deposited close to external doors and windows, this suggests that the cat was responding to a threat from outside the home, such as a non-resident cat entering its territory. If the first urine marks were mostly deposited on furniture in rooms, around doorways, corridors or staircases, this suggests that source of stress is the relationship with resident cats. Cats will also spray mark on mirrors, and electrical items. The following table summaries common patters of urine deposition in problem situations.

Indoor Marking Inappropriate Elimination
Characteristic patterns in urine and faeces deposition:
  • Initial locations are around cat flap, external doors and windows: external threat from non-resident cat(s) in the resident cat's outdoor territory.
  • Initial locations are entry points to internal rooms, on landings and in corridors: internal conflict within home
  • Marking sites are initially at the cat flap, and expand into the house: potential home invasion by non-resident cat
  • Initial deposits on new items in the household, shoes or shopping bags: insecurity and reaction to unfamiliar odours that have been brought into the home on those items.
  • Single indoor toilet location or substrate (litter box available): location or substrate of litter tray is unsuitable, or cat may be afraid to use the litter tray
  • Single indoor toilet location or substrate (no litter box, cat previously used garden latrine): cat is unable to use outdoor latrine because it is unusable (e.g. waterlogged, frozen, or paved over), or inaccessible (e.g. cat is unwell, or a dog now inhabits garden where the latrine is sited), or it is defended by other cats as part of their territory (e.g. despotism)
  • Multiple indoor toilet locations and substrates: cat is unable to use a regular latrine due to conflict with other cats, aversive experiences during elimination (e.g. pain associated with FLUTD, or owner punishment)

The Relationship Between Resident Cats

Example of a diagram illustrating the relationships between cats within the same household

In situations of both marking and elimination behaviour within multi-cat households, the relationship between resident cats is often an underlying factor in problem expression. Competition between resident cats for access to constrained resources, such as food, a litter tray or an outdoor access point, leads to stress. Cats may use urine spray and claw marking in an attempt to organise access to space; trying to maintain temporal and spatial separation from one another. This is intolerable for owners, and is ultimately dysfunctional for the cats. Hostile encounters around the litter tray or an outdoor access point may force less confident and assertive cats to find other places to eliminate within the home. An assessment of the relationship between resident cats is therefore an important part of the investigation process.

Owners cannot be relied upon to assess the relationship between cats, because they frequently misinterpret feline communication and social relationships. For example, they may interpret all chasing behaviour as playful, and underestimate the significance of fights and aggressive vocalisations between cats. Most importantly, positive signs of stress and anxiety, such as the typical whining, agitation and restlessness observed in dogs, are very noticeable, but negative signs, such as the typical inhibition and reduced activity observed in cats, are often overlooked.

Within multi-cat households, there may also be "factions"; groups of cats that show affiliative behaviour with each other, but which are indifferent or hostile toward other resident cats. A simple way to evaluate the relationship between resident cats, and identify factions, is to create a diagram of affiliative and aggressive behaviours between them (see example). This can be annotated with information about changes in the relationship, such as after the death of one of the resident cats.

The names of the cats are written in a circle, and information about behavioural signs of the relationship between each pair of cats is added to the diagram. Positive affiliative behaviours include allorubbing and allogrooming, tail up and trilled greeting between cats. Overtly aggressive behaviours include chasing, hissing or spitting and physical attacks, as well as more passive threats such as staring eye contact, and threatening body or facial posture. Positive and negative interactions and their direction should be noted on the diagram (see example).

The diagram should indicate the general relationship between the cats, and whether there are factions within the group. In combination with information about where in the home the cats (or factions) tend to spend time, this diagram can provide useful information about where to place resources so that they are easily accessible by individual cats and factions. It can also provide an indication of social problems that may need to be resolved. Constructing the diagram with the owner also offers a valuable opportunity to explain feline communication and social organisation with the owner.

Identifying the Culprit

It is very important to properly identify the culprit(s) of the indoor housesoiling, particularly when treatment with psychoactive medication is being considered. It is common for more than one cat in a multi-cat household to be involved, particularly when the problem is indoor spray marking.

Identifying Cats Responsible Faecal Soiling

If faecal soiling is involved, then a small amount of indigestible material is added to each cat’s food for several days and the faeces are inspected. When added to the diet, crushed sweet corn or finely chopped raw carrot are both easily visible in faeces, and are unlikely to cause gastrointestinal problems.

Using Fluorescein to Identify Cats Responsible for Urine Marking or Elimination

When ingested, fluorescein dye is excreted intact in urine, and can be made to fluoresce using a UV lamp. This can be used to identify the cat responsible for leaving urine deposits. A dose of 50mg/cat once daily is given, which is equivalent to the amount of dye in the tips of six fluorescein test strips (commonly used for ulcer detection in ophthalmology)[3]. However, the fluorescence of fluorescein varies considerably with pH[4], so that it only strongly fluoresces in a neutral or alkaline solution; in an acidic solution it may hardly fluoresce at all. Spots may therefore need to be sprayed with a buffer solution of sodium bicarbonate (baking soda), which will produce a pH of around 8, before testing with a UV lamp.

  • Fluorescein is available as large sterile paper strips, for ophthalmic examination. These contain approximately 9 mg of fluorescein per strip, but this should be checked with the manufacturer.
  • The dye containing tips of six test strips are torn off and either rolled to fit into gelatine capsules, or chopped up and mixed with food.
  • This dose is given once daily for 1-3 days, depending on results.
  • Urine sites are checked daily for fluorescence with a UV lamp (now cheaply available for checking of paper currency).
  • If necessary, each site is lightly sprayed with an aqueous solution of sodium bicarbonate (baking powder; approximately 1 tablespoonful in 125ml water).
  • Leave 3 to 5 days between testing successive cats, to allow all of the dye to be excreted.

Although fluorescein is water-soluble and can usually be removed with normal cleaning, it can leave yellow stains on light coloured fabric, leather, carpets or wall paper. Owners must be warned of this, because considerable damage can result. In addition, it is best to start by dosing those cats which are believed least likely to be responsible for the urine deposits. Using this method it is possible to make an identification based on exclusion, and therefore avoid any dye contamination of the owner's home.

Use of Video Cameras

Most mobile devices have a video capability, and webcams are relatively cheap. Movement triggered apps and software enable the video function to be activated when a cat comes into range. If certain locations are regularly marked or soiled, movement triggered video recording can be used to identify the culprit. This can be particularly valuable when it is suspected that urine marks are being deposited by non-resident cats entering the home.

Cooperation Between Cat Owners

According to Pet Food Manufacturers Association data, the pet cat population in the UK more than doubled between 1965 and 2004, with an estimated 10-million cats being kept as pets in the UK (2010)[5]. This increase in population density may contribute to problems of intercat aggression, house soiling and indoor marking. In urban areas with high pet cat population densities, veterinary practices may need to encourage or organise cooperation between neighbours in a community in order to improve outdoor space for cats (for example, improving availability of outdoor latrine sites). Providing resident cats with access to a stimulating outdoor environment, with densely planted borders, trees, resting sites, and wildlife (birds and insects) improves their quality of life.


  1. Beaver, S. (1989) Housesoiling by cats: a retrospective study of 120 cases. "JAVMA". 25:631-637.
  2. Borchelt, P.L., Voith, V.L. (1986) Elimination behavior problems in cats. "Compend Contin Educ Pract Vet". 197-207, 1986.
  3. Neilson, J. (2003) Feline House Soiling: Elimination and Marking Behaviors. "Veterinary Clinics of North America: Small Animal Practice". 33(2):287-301.
  4. Sjoback, R., Nygren, J., Kubista, M. (1995) Absorption and fluorescence properties of fluorescein. "Spectrochimica Acta Part A". 52. 7-21.
  5. Murray, .K., Browne, W.J., Roberts, M.A., Whitmarsh, A. Gruffydd-Jones, T.J (2010) Number and ownership profiles of cats and dogs in the UK. "Veterinary Record". 166:163-168.

Also see:

Inappropriate Elimination - Cat
Indoor Marking - Cat

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