The PDSA's most recent Animal Wellbeing Report surveyed 12 334 cat owners and 1699 of their veterinary surgeons. It found that 25% of the UK population has a cat — an estimated 11.1 million cats (PDSA, 2015). Many of these cats are living in multi-cat households, despite 1.7 million owners recognising that their cats ‘aren't keen on each other’. The report also found that within these households a substantial proportion of the cats are forced to share their resources with other cats, with 50% sharing litter trays and 58% sharing water and food bowls.
Yet companion and feral cats have evolved from a species (Felis silvestris lybrica — the African/Arabian wildcat) that only about 12 000 years ago was still to embark on the domestication process (Serpell, 2000). These ‘wildcats’ were solitary hunters; they had to be, as prey was scarce and competition from another cat within an individual's territory immediately reduced a cat's capacity to perform that most basic of functions — to thrive and survive (Fitzgerald and Turner, 2000). Each cat, as do present day feral cats, required 12 to 15 rodents per day to survive. To successfully kill 12 rodents, with an approximately 10% success rate, a cat needed access to a minimum of 120 opportunities to hunt. As this precarious existence was occurring in harsh conditions, another cat attempting to share the resources provided by the environment would not enhance either cat's chances of survival (Bradshaw et al, 2012).
As a consequence of this relatively recent evolutionary journey and the fact that human settlements throughout the world (including many European cities) still support large populations of feral and stray cats (that continue to require their ‘wildcat’ behavioural repertoire to enable survival), cat behaviour has had only limited opportunity to change from that of its wildcat ancestor and the presence or proximity of other cats remains a source of distress for many cats living in a domestic environment. As a result, cats will naturally live either alone or in groups (rarely more than 10 adults) of related, female cats with some juvenile male offspring (Bradshaw, 2012). Within these groups individual cats may form attachments to some specific cats while avoiding other members of the group (Crowell-Davies et al, 2004).
What is communication and what do cats use it for?
Communication (from Latin commūnicāre, meaning ‘to share’) can be defined as the process of sending a message from one individual to another with the purpose of modifying the behaviour of the receiver(s) of the message (Ley, 2016a). However, a problem arises in intra-species communication between felines as their ethology is based around maintaining a distance between cats and consequently their communication repertoire is also largely intended for this purpose. As a result, much of the cat's communication system is designed to enable cats to remain at a distance and this means that the nature of the communication is most efficiently and safely designed to be ‘read’ while cats are still at a considerable distance from each other, enabling them to select to maintain, and if necessary increase, that distance (Bradshaw et al, 2012).
Aggression is part of an animal's communication system — an unambiguous message to another individual that the animal is not comfortable with its proximity and requires a greater distance between them (Mills et al, 2010). As a consequence, when feline communication is examined, much of the signalling used may also be considered to be aggressive in its nature as, whether passive or overt, it is intended to maintain a distance between two or more individual cats. As a self-reliant and solitary hunter, overt physical conflict would be a considerable threat to survival — hence, cats avoid overt fighting that would be likely to lead to injury and death through starvation and/or infection (Ley, 2016a). As a result, much of feline communication may be considered to be a form of passive aggression. Some cats may even be considered to be passively offensive in their aggression — actively using psychological bullying tactics (rather than overt physical aggression), to prevent other cats from gaining access to resources e.g. the cat that sits at the base of the stairs casually washing itself or seeming to rest, can prevent upstairs cats from gaining access to food, owners, latrines and the cat flap that are located downstairs (Heath, 2016). Yet, as such subtle aggressive behaviour does not result in obvious injury or flying fur, many cat owners overlook this distance creating behaviour and the distress experienced by their cats continues.
As a natural consequence of the cat's unlikelihood of actually encountering or living alongside other cats in its natural environment, the probability of intense and overt aggressive incidents in nature is small (Bradshaw et al, 2012). In social species, such as the dog, where repairing relationships post conflict is essential to the maintenance of the social group and the safety of the individual, it is important that the species develop a range of post-conflict behaviours. For cats living outside a domestic framework, such behaviours would be redundant to their behavioural repertoire and a waste of energy. Should an intra-specific (between members of the same species) encounter occur, the individuals should disperse post conflict and should not, naturally, meet again. Consequently, cats (whether in domestic situations or feral) lack post-conflict rituals and have no reconciliation strategies that can be used (Bradshaw, 2012), leading to the development of significant levels of chronic stress between cats that have previously engaged in aggressive signalling, no matter how subtle, but that are forced to regularly encounter each other in a domestic environment.
Cats – I see no cats. Helping cats to avoid the need for aggression
Despite their origins, some cats can cope with intercat relationships and the proximity of specific, individual cats (Bateson, 2000) — but the circumstances seem to be limited to:
It is currently thought that cats can continue and extend their social learning until up to 2 years of age (Bradshaw et al, 2012), but only if they have had opportunities to meet friendly cats from outside their family group (mother and litter siblings) by 7 weeks of age (Overall, 2013). Despite this, some cats may be genetically predisposed towards more sociable behaviour, and it has been known for some adult cats to form social relationships with another adult or a kitten; but this is the exception and should never be assumed to be a likely event, even with careful introductions.
However, the majority of cats fall outside of this narrow range of potentially sociable individuals and would prefer to live solitary lives (Landsberg, 2013). Consequently, if cats are to cope in a multi-cat environment, not only must inter-cat communication enable these cats to avoid the proximity of other cats, but household management of the multi-cat home must also make this a priority (Seksel, 2016). Cats will attempt to organise this tricky process by time sharing — using chemical communication and environmental learning to avoid coinciding at the site of a resource (Bowen and Heath, 2005). Unfortunately, cat owners frequently misunderstand how detrimental the stress associated with the anxiety of expected inter-cat confrontations can be for the cat. Added to this is the distress associated with the frustration (associated with the failure of natural feline distance creating communication) of multi-cat living. Hence, many cats are forced to come together and encounter one another, at close proximity, in environments where they require access to highly valued resources — such as food, latrines, water, owner attention, and warmth (Seksel, 2009) (Figure 1). Despite the cat's attempts to manage encounters at such resources, e.g. holding back from access to food bowls, over-eating or pulling paw-fulls of food from bowls (to avoid having to eat in close proximity to con-specifics (animals of the same species) and moving from one area of a room to another by skirting the room (Heath, 2016), such subtle attempts at distance creation often remain unnoticed by owners.
Hence, maintaining the welfare of individual cats within a multi-cat group means ensuring that every cat can get instant access to each and every resource that it might need, without coming into visual contact with another cat (Rochlitz, 2009) (Table 1).
| Essential resource management includes: | |
|---|---|
| Creating a suitable environment | Comment |
| Ensure that no cat has to pass another's ‘territory’ to gain access to an essential resource | Identify where each cat spends most of its time and provide all essential resources (beds, litter tray, water, food) in each of these areas |
| Enhance the cats use of a 3D environment | Make shelves and work tops accessible to the cat |
| Cat ‘trees’ and other raised areas should be varied and plentiful — at least one in every area/room that a cat uses | Designs should provide observation (open) and resting (closed or with sides) areas |
| Enhance the cat's capacity to access areas | Tunnels and boxes (Figure 2) provide safety while travelling from place to place (especially hallways). Ensure all have two openings to enable escape if another cat jumps in! |
| Ensure that all shelves are wide enough for cats to pass each other and offer sufficient variation in height and angle | Having to make eye to eye contact or engage in a ‘stand-off’ can damage relationships |
| Cats prefer to sleep alone | Beds, igloos etc. should be only large enough for one cat! |
| Elderly cats also require the safety of raised areas | Provide ramps and low steps |
| If one cat ‘guards’ the back door area | Consider an extra cat flap on a front door |
| If cats can see other cats from resting areas or from windows | Make windows opaque with attractive, temporary plastic sheets or other material |
| Prevent outdoor cats from entering the home | Use a microchipped cat flap and keep doors and windows closed |
| If outdoor cats are marking around door-ways or lurking there | Keep this area cleaned with biological washing powder. Provide large ornamental plant pots for your cat to hide behind and use home harvested pheromones to wipe their surfaces |
| If other cats are using the garden | Consider cat-proof fencing |
| Allow each cat to be a cat! | Comment |
| Provide plenty of scratch posts in a variety of materials, positions (vertical and horizontal) and rooms. Cat trees can double for this purpose | Every cat will have a different preference. Do not forget well-travelled passageways. Place them where cats have to come together – allowing appropriate territorial signalling |
| Place litter trays around the house so no cat has to run the gauntlet past another cat to reach one | One tray per cat plus one (all in separate rooms) is a minimum |
| Toys should resemble prey — small and furry or feathery | Constantly rotate the toys during play sessions — every few minutes |
| Erratic movement — such as provided by ‘fishing-rod’ type toys — is popular | Try to end the game over a tasty morsel — this can relieve frustration and reduce injury to other cats and owners |
| Play ‘retrieve’ | Use small jingle balls or scrunched up paper and tunnels to increase the fun |
| Teach your cat new tricks and increase mental stimulation | Rewards and target training will make your cat easier to handle and will provide you both with a lot of fun |
| Encouraging appropriate mental stimulation | Comment |
| Meet the need to work for food | As an alternative to food bowls, offer multiple opportunities for small meals involving puzzle feeding. NEVER FEED CATS TOGETHER |
| Use mental and physical energy | Even sedentary cats will move around and investigate their environment if small tasty meals are the reward. If the cat is elderly, provide ramps and steps to make this easier |
| Good pet shops can give advice on a wide array of cat puzzle feeding toys | But plenty of household items can be used — toilet roll centres, yoghurt pots, tennis balls with holes |
| Cats like to be able to see their food | Select transparent toys or those with holes large enough for the cat to be able to see its ‘prey’ |
| Cats never choose to eat, drink and toilet in one place | These resources should be separated and there should be at least one set per cat placed in the rooms that individual cats like to use |
| Some cats prefer flowing water | Offer choice and remember that water should be offered in ceramic dishes that are full to the brim |
But surely inter-cat problems only occur in multi-cat households
All cats experience a motivation to thrive and survive and access to adequate resources is part of that survival strategy (Bradshaw et al, 2012). Whether a cat is well fed by its owner or not, the regular investigation of the cat's environment for potential hunting opportunities is part of the cat's innate behavioural repertoire (Fitzgerald and Turner, 2000). As a consequence of this any cat seen within the home (core territory) or home range (the area that the cat regularly patrols and investigates) will be considered a competitor for essential resources and consequently both cats will experience a motivation to defend its territory (Heath, 2016).
Confident cats will wander freely around a wide area, often entering the home range of other cats. The effect of this activity on timid cats is that they retreat to an ever decreasing home range that may eventually become the house and door-step, as the cat becomes increasingly anxious, or even fearful, of overt threats from neighbouring cats (Ley, 2016b). However, for these more timid individuals, the stress associated with the sight and smell of other cats remains, leading to cat flaps, open doors and windows being sites of particular stress as neighbouring cats will often use these while owners are out of the home or at night. These invasions inevitably enhance stress for individual cats and between existing cats within the household (Bowen and Heath, 2005).
Although cat flaps designed to limit invasions may reduce such problems, they do not remove the threat from the outdoor cat that marks the area around a door, or sits and waits by a door or within sight of a window — making it increasingly difficult for the indoor cat to cope. Observation of such cats can lead to an indoor cat becoming increasingly frustrated and even attacking another household cat (exacerbating any existing social frictions) or passing owner (Frank, 2003). In addition, the mounting and chronic exposure to stress experienced by the cat that is failing to cope with social encounters with other cats, can lead to multiple health (e.g. urinary, gastric and skin complaints) and behaviour (e.g. over-grooming and urine marking) problems (Rodan and Heath 2016). The constant movement of cats in and out of a cat's home range (through owners moving in and out of the area, or the demise of a cat and replacement by another) further exacerbates the social tensions experienced by most domestic cats (Heath, 2016).
Why do cats play?
Many owners use the existence of ‘play’ between cats as evidence of a good and healthy social relationship. However, there can be a fine line between play and aggression. Play between adult animals (dogs being the exception) has been described as rare (Mills et al, 2010) and can be defined as behaviour performed for its own sake and not fulfilling any obvious biological need. Play between kittens, and when kittens interact with inanimate items, is usually associated with developing predatory skills. Adult cats also enjoy short bursts of energetic play with prey type items (Ley, 2016b). However, it is this author's opinion that it is reasonable to question whether it is safe to ever describe inter-cat activity between adults as play?
Although many bonded cats may seem to enjoy play fighting and chasing each other, the posturing and pouncing associated with adult cat play may quickly lead to one cat becoming fearful and to both cats becoming frustrated regarding the lack of success associated with their distance maintaining communication. Play will involve retracted claws, gentle bats and significant periods for recuperation for repositioning into less vulnerable positions. However, even gentle biting can escalate to a cat hissing, crying or attempting to escape at speed, all of which behaviours can quickly initiate an overtly aggressive attack and a serious breakdown in the cat's relationships with resulting long-term tensions (Ley, 2016b).
Marking and communication — why marking is essential to feline welfare
Owners often overlook the importance to cats of olfactory communication. Pheromone-based ‘scent’ messages enable information to be safely left in an environment for many days without the need for signalling cats to meet. These pheromone/odour based signals include the social and environmental rubbing associated with facial pheromones (Mills et al, 2013) and the urine (associated with territorial maintenance and passive aggressive behaviour (Heath, 2003)) and scratch (associated with alarm and territorial signalling (Frank, 2003)) marking. Odour would also appear to play an essential role in maintaining social cohesion in cat colonies (Bowen and Heath, 2005), as members of colonies are thought to carry a communal scent profile. The use of olfactory communication enables both social recognition and environmental orientation, removing the need for the cat to rely on visual recognition of companions and places (Bradshaw et al, 2012).
The cat's natural requirement for olfactory feedback to enable it to experience a concept of safety and security in a familiar social and physical environment (Heath, 2003) is severely disrupted when a cat is removed from its normal environment (e.g. to visit the veterinary surgery or cattery). Consequently, when other household cats return to the home smelling strongly of stimuli met in the environment outside the home, this can lead to a lack of recognition and potential loss of social acceptance, even between cats that were previously closely bonded (DePorter, 2016). An owner's overzealous household cleaning procedures or washing the cat's bedding may also disrupt environmental cues within the household, leading to disorientation in individual cats, increased anxiety and enhanced distance creating signalling around resources. Hence, many cats benefit from the presence of synthetic analogues of feline pheromones associated with safety within the home (Mills et al, 2013).
Keeping communication on the ‘lighter’ side — managing resources
If cats are already showing signs of passive (subtly controlling the movement and access of other cats, running away from or hiding from other cats, scratching items or urine marking) or overt (chasing, swiping at or cornering other cats) aggression, the cats should be separated and then carefully re-introduced (Heath, 2016). This is likely to require the assistance of a clinical animal behaviourist (Landsberg et al, 2013) (see Association for the Study of Animal Behaviour, Animal Behaviour and Training Council or Association of Pet Behaviour Counsellors websites for registers of appropriately qualified and experienced clinicians). However, owners may have to accept that the limited space that their home provides is incapable of providing the required welfare needs of more than one cat and that re-homing should be the welfare option of choice for one or more of their feline companions (Overall, 2013). Cats that are struggling to cope with the proximity of cats that live outside their home will also need extra support (Heath, 2016).
For those cats that are currently capable of tolerating each other, no owner should make assumptions that this will continue without appropriate environmental interventions regarding access to resources (Seksel, 2016). Without the capacity for repairing relationships, waiting until a feline relationship has broken down before intervening means that intervention is simply too late in arriving!
Can a sense of safety and wellbeing be enhanced with pheromones?
Cats use different types of pheromones to identify areas of safety and areas where conflict has previously occurred or can be expected (DePorter, 2016). By carefully cleaning previous ‘warning’ messages with appropriate products and replacing them with chemical signals of safety and security through the use of synthetic analogues of feline peheromones, the cat can be assisted in better managing its home environment. However, many owners erroneously consider it logical to place these synthetic analogues of natural signals of enhanced safety in areas where their cats experience inter-cat friction — but the cat has already learned that such environments predict conflict. Pheromone products are best situated in the areas where individual cats return to achieve safety (Mills et al, 2013) and consequently, each feline haven within the home will benefit from appropriate pheromone support.
Feliway Classic (Ceva) has been shown to be beneficial in reducing urine spraying (White and Mills, 1997) and scratching problems. If these signs are not present, but there are signs of direct conflict between the cats (chasing, staring, obstructing access to areas of the home), the newly available synthetic analogue of cat appeasing pheromone — Feliway Friends (Ceva) — has been shown to be useful in reducing inter-cat conflict (Cozzi et al, 2010; DePorter et al, 2014). If owners are introducing novel social or environmental changes or have noticed a combination of all of the above signs, both forms of Feliway should be used, concurrently. However, once passive or overt aggression has developed between cats there is a need for referral for specialist support from a clinical animal behaviourist.
Conclusion
Communication is an essential part of social living. But the cat has not evolved as a member of a social species and although the domestic cat's owners become a very important part of the cat's life, social relationships with other social animals — including other cats and other humans — are far from guaranteed (Heath, 2003). Consequently, the line that can be drawn between the cat's social communication and aggression remains subtle, yet many owners remain convinced that cats require the companionship and proximity of other cats.
From the above, it is clear that a substantial number of cats living amongst other cats (within or outside their home) fail to get their basic welfare needs met. This results in problems with access to basic resources and affected cats are likely to express their distress through the use of inter-cat aggression. However, cats excel at voting with their feet — when environmental provision becomes impoverished and cats fail to cope, many of them leave home (Rowan and Williams, 1987). But for those cats that continue to live amongst other cats, the distress associated with living in an atmosphere of constant competition for essential resources, and the associated aggression, will lead to serious welfare problems and potentially result in poor physical health (Rodan, 2016). Owners have a responsibility to become familiar with and meet all of their cat's welfare needs within the home (Rodan and Heath, 2016). In addition, the veterinary profession has a responsibility to educate cat owners regarding how they can meet the needs of their cats (Rodan, 2016).