The domestic cat has evolved from the African wild cat (Felis silvestris libyca), a semi-arboreal carnivore with an essentially solitary lifestyle. Cats do not have as wide a behavioural repertoire [facial expression, body posture, tail position] for visual communication as, for example, the highly social, group-living dog. They are more likely to respond to poor housing conditions by becoming inactive and by inhibiting normal behaviours such as feeding, grooming, exploring and playing than by showing abnormal behaviour (McCune, 1992; Rochlitz, 1997a). Sick cats will respond in a similar way. Therefore, keeping cats in a species-appropriate environment that encourages a wide range of normal behaviours will not only enhance the animals' welfare, making them better subjects for scientific investigation (Poole, 1997) but will also make it easier for caretakers to detect when an animal is unwell.

The emphasis in laboratory animal housing has been shifting from an `engineering' approach [specifying cage dimensions and features, and management procedures] to a `performance' approach [providing housing conditions and management procedures that enable the animals to reach certain performance standards] (National Research Council, 1996). The `performance' approach offers more flexibility, while the `engineering' approach provides a basis for the establishment of minimum requirements. This chapter presents recommendations for the housing and care of cats in laboratories, which are based on recent research and include both 'engineering' and 'performance' approaches.
  

Even though they have evolved from a solitary species, domestic cats are social animals who regularly interact with conspecifics (Leyhausen, 1979; Sandell, 1989). In most instances, cats will benefit from being housed with others provided there is sufficient space, easy access to feeding and elimination areas and an adequate number of retreats and rest places.

Many factors will determine the ideal group size, but it seems that 20 to 25 individuals is the maximal number for cats in laboratories (James, 1995; Hubrecht and Turner, 1998). Cats who fail to adapt satisfactorily to group-living generally adapt well to pair-housing. If a cat shows persistent incompatibility with other conspecifics she or he should be housed singly (Figure 1). If single-housing is necessary, the cage should be arranged in such a way that the cat has visual contact with other cats. While some authors suggest that tomcats should be housed singly, others have shown that they can be housed successfully with other males (Hart, 1980), with neutered males (Podberscek et al., 1991), or with neutered females. Queens in the last two weeks of pregnancy, and queens with unweaned kittens should be housed without other cats.

Figure 1. Cats who do not adapt to living harmoniously in groups or in pairs should be housed singly.

The introduction of a new animal to a group should be done slowly, under careful supervision. Initially, the resident cats should be able to get familiarized with the stranger without risk of overt aggression. To accomplish this, the new cat has to be kept in a separate cage within the group's enclosure. He or she must have access to a hiding box in the cage, in order to escape the attention of resident cats. Usually within two weeks, the newcomer can be safely released into the enclosure without risk. The use of synthetic analogues of naturally-occurring feline facial pheromones may facilitate the harmonious introduction of a strange cat into an established group (Pageat and Tessier, 1997).
 

The enclosure must be large enough to allow cats to express a wide range of normal postures and behaviours, such as stretching, exploring and playing, and to permit the caretaker to carry out routine procedures easily. In order to minimize social tension and prevent aggressive conflicts, and for reasons of hygiene, there should be a distance of at least 0.5 m between the various functional areas for feeding/drinking, resting, scratching and defecating/urinating.

Group-living cats lack distinct dominance hierarchies and post-conflict mechanisms such as reconciliation (van den Bos and de Cock Buning, 1994a; van den Bos, 1998). They are not adapted to living in close proximity to one another and reduce the likelihood of aggression by keeping a distance between themselves (Figure 2; Leyhausen, 1979). Bernstein and Strack (1996) described the use of space and patterns of interaction of 14 unrelated cats who lived together in a single-storey house, at a density of one cat per 10 m² . There was very little aggression and no fighting among the cats. Individuals peacefully co-existed because they were able to avoid one another for most of the time. If an enclosure is too small, there may be an increase in agonistic encounters, or the animals will attempt to avoid each other by decreasing their locomotor activity (Leyhausen 1979; van den Bos and de Cock Buning, 1994a). In a study of laboratory cats, daily activity levels dropped by 60 per cent when the animals were moved from a large enclosure [2.2 m² per cat] to a considerably smaller one [0.32 m² per cat] (Rochlitz, 1997b). Neutered, indoor-only pet cats kept in pairs maintain a distance of one to three meters from each other most of the time (Barry and Crowell-Davis, 1999). Kessler and Turner (1999) propose that there should be 1.7 m² per cat for group-housed cats in shelters. In research institutions, the minimum floor space should be 1.5 m² per weaned cat. It should be emphasised that the minimum floor space requirement for cats is determined by their socio-spatial needs rather than by body weight.

Figure 2. There should be enough space for cats to have some privacy. Enclosures should contain structures that enable cats to use the vertical dimension.

Cats use raised structures more often than the floor of their pens (Podberscek et al., 1991; Rochlitz et al., 1998). High vantage points are used more frequently than low ones (Smith et al., 1994; Rochlitz, 1997b). As the vertical dimension is so important for cats, the enclosure of single-, pair- and group-housed animals should be at least 1.5 m high so that elevated resting surfaces can be installed well above ground level. Walk-in enclosures [2 m high] are ideal, as they also allow caretakers to easily enter and interact closely with the cats.

In some instances, it may be necessary to house a cat singly for recovery after a clinical procedure. This should be for as short a time as possible. The cage should have at least 1.5 m² of floor space, but it does not have the height of a walk-in enclousre. However, it should be no less than 1 m high so

• that the cat can stretch fully in the vertical direction, andthat a shelf can be installed in such a way t
• that the cat can comfortably rest on it and freely move on and under it.

Cages should not be stacked one on top of the other. Placing the cages on a shelf at waist height or higher will make access easier for the caretaker.
 

Beyond a certain minimum size, it is the quality rather than the quantity of space that is important for cats (Rochlitz, 2000). Domestic cats are agile, semi-arboreal animals who are skillful climbers. They use elevated areas as vantage points from which to monitor their surroundings and the approach of people and other animals (DeLuca and Kranda, 1992; Holmes, 1993; James, 1995). Enclosures should contain structures that enable cats to make maximal use of the vertical dimension, such as climbing frames, raised walkways, hammocks, and platforms or shelves placed at different heights (Figure 1, Figure 2). Slanting boards, steps and poles will help kittens and small cats to reach the raised areas.

There needs to be a sufficient number of rest areas for all cats in the enclosure, as cats like to rest alone rather than with others (Podberscek et al., 1991, Bernstein and Strack, 1996). Rest areas should have comfortable bedding (Figure 3). Cats who sleep on soft surfaces have longer periods of deep sleep than those who sleep on hard surfaces, suggesting that they feel more secure (Crouse et al., 1995). Cats prefer polyester fleece to cotton-looped towel, woven rush-matting, or corrugated cardboard as bedding material (Hawthorne et al., 1995). If there is not a sufficient number of comfortable rest places, the animals will use their litter trays for this purpose (DeLuca and Kranda, 1992; Rochlitz, 1997b). This is undesirable because it prompts other cats to urinate and defecate outside the litter trays.

Figure 3. Rest areas should have comfortable bedding.

Hiding is a behaviour that cats frequently display in response to changes in their environment, as well as to avoid interactions with other cats or with people (McCune, 1992; James, 1995; Rochlitz et al., 1998; Figure 4). A study of pair-housed cats found that the animals spent 50 per cent of the time out of sight of each other (Barry and Crowell-Davis, 1999). Visual barriers, such as vertical panels, trellises and curtains, can be used to divide the enclosure into separate spaces enabling cats to get out of sight of others. In a study of the behavioural and physiological correlates of stress in laboratory cats, hiding behaviour was negatively correlated with urinary cortisol concentration (Carlstead et al., 1993). This suggests that hiding functions as a stress-buffer. Therefore, cats should always have access to comfortable hiding places [e.g., boxes, deep-sided trays] in addition to open rest areas [e.g., shelves]. A raised, partially enclosed structure is useful as it conceals the cat who can monitor her or his surroundings at the same time.

Figure 4. Cats need retreat areas where they can hide.

Each cage of individually housed cats must have a litter tray. In group-housing, there should be at least one litter tray per two cats (Hoskins, 1996). Trays have to be cleaned once or several times daily, because some cats will not use a tray if it has already been soiled.

In a study of dominance in a group of female cats (van den Bos and de Cock Buning, 1994b), lower-ranking animals spent little time on the floor, were most often found on shelves and appeared to be less mobile than higher-ranking individuals. Lower-ranking cats lost weight over time, and would use their rest sites for urination and defecation. Higher-ranking cats occupied the floor area, moved around the colony room more freely and tended to gain weight. These findings indicate that it is advisable to place feeding stations, water bowls, resting shelves and litter trays in a number of different sites, to prevent certain cats from monopolising one resource and denying others access to it.

Surfaces for claw abrasion and olfactory marking [e.g., scratch posts, rush matting, carpet, wood] as well as a variety of play objects should be provided for social-housed cats (Figure 5) as well as for individually caged cats. Small, mobile objects with a complex surface texture, are the most successful at promoting play (Hall and Bradshaw, 1998). De Monte and Le Pape (1997) found that a tennis ball was a more effective enrichment tool than a wooden log, for single-caged animals. Cats are intelligent animals and quickly lose interest in such play objects (De Monte and Le Pape, 1997). Varied toys should, therefore, be substituted regularly to ensure their novelty effect. Most cats play alone rather than in a group (Podberscek et al., 1991), so the cage has to be large enough for cats to play without disturbing others.

Figure 5. Cats should have access to appropriate surfaces for scratching, as well as to a variety of toys.

Another environmental enrichment technique is to increase the time animals spend in pseudo-predatory and feeding behaviour. McCune (1995) suggests putting pieces of dry food into containers with holes through which the cat must extract individual pieces; such a device stimulates play and pseudo-predatory behaviour (Figure 6).

Figure 6. Dexterity is required to retrieve pieces of food from the puzzle (Photo by Geoffrey Loveridge, 1997).

Windows are an excellent way of providing interesting stimulation for confined cats (Loveridge, 1994). DeLuca and Kranda (1992) found that animals housed as a group spend most of the day sitting on a window perch, watching activity in the outside hallway. Windows should have deep sills or nearby elevated resting surfaces.

Consideration should be given to providing containers of grass. Most cats like to chew and ingest fresh grass, which helps them to eliminate furballs [trichobezoars]. Catnip (Nepeta cataria) is also enjoyed by many cats, either as a dried herb or when contained in toys.

Control over the immediate environment is a feature of good animal housing (Broom and Johnson, 1993). An enclosure with separate functional areas [e.g., pen with an outdoor run; interconnected pens; vertical divisions within a pen], species-appropriate furniture [e.g., shelves; hiding box] and sensory access to the surroundings [e.g., window], allows cats some control over their physical and social environment. They can then make a variety of behavioural choices [e.g., climb on an elevated platform to get a better view; move behind a visual barrier to be alone] for optimal environmental adjustment and general well-being.

The floor of all cat enclosures should be smooth, non-slip and easy to clean. Wire-mesh or grid floors are not suitable, as they are uncomfortable for cats, and may trap and injure their extremities [digits, paws and tails].
 

To facilitate handling and minimize stress during routine and experimental procedures, cats must be well socialised to humans. One of the best ways to achieve this is to ensure that young kittens are handled and spoken to on a daily basis. This is particularly important between two and seven weeks of age, the kittens' sensitive period for socialisation to people (Karsh and Turner, 1988; Figure 7). This regular, gentle handling should continue throughout the cat's life. Other factors that influence the sociability of cats to humans are summarized in Turner (2000).

Figure 7. Young kittens should be stroked and handled gently, on a daily basis.

Cats respond strongly to humans in their environment, and they organise their daily activity patterns around the caretakers' activity (Randall et al., 1990). In research facilities, cats demonstrate a clear preference for human contact over toys (DeLuca and Kranda, 1992). Hoskins (1995) examined the effect of human contact on the reactions of cats in a rescue shelter. Animals who were regularly handled by a familiar person allowed an unfamiliar person to hold them for a longer period than naïve cats. This effect is likely to be beneficial in the laboratory setting, where cats are handled on a regular basis by the [familiar] caretaker, and on an irregular basis by the [unfamiliar] researcher (Figure 8).

Figure 8. Cats who are well socialised to humans show little or no resistance during research-related handling procedures.

Cats show signs of stress [altered behaviour and raised urinary cortisol levels] when they are subjected to an unpredictable caretaking routine, and when technicians stop petting them and talking to them (Carlstead et al., 1993). Sudden changes in husbandry routine or the environment should be avoided. If changes need to be made, they should be introduced slowly and under careful supervision.

Caretakers need to be knowledgeable about the species-typical behaviours of cats. They should enjoy working with and for the animals. The importance of positive social interactions between care personnel and their animals cannot be over-stated. While cleaning and feeding times provide some opportunities for interactions, a period of time that is not part of routine procedures should be set aside every day for caretakers to be with their cats. Some cats may prefer to be petted and handled, while others may prefer to interact via a toy (Karsh and Turner, 1988). Most cats enjoy being groomed, and this can be a good time to detect whether an animal has lost weight or is otherwise unwell. Social contact with humans is particularly important for individually caged cats.
 

Cats should be obtained only from designated breeding establishments [class A dealers].
 

This chapter describes the needs of cats kept in research institutions for a stimulating, well-designed housing environment and appropriate considerate care from personnel. Attention to these housing and care requirements will result in healthy, friendly, well-adapted cats, thus enabling scientists to use fewer animals in their research and obtain better results.
 

I would like to thank the Blue Cross Adoption Centre for its help with photographs, and Professor D.M. Broom for providing the facilities to write this chapter.

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Irene Rochlitz is a veterinarian with an interest in animal behaviour and welfare. Her Ph.D. was on the welfare of cats kept in confined environments. She is a research associate with the Animal Welfare and Human-Animal Interactions Group at the University of Cambridge, UK. She combines research into issues affecting the welfare of cats with clinical work in veterinary practice.

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