Space is always at a premium in an animal facility, making it necessary to maximize the efficiency of the available space in order to meet or exceed Guide for the Care and Use of Laboratory Animals1 regulations. A facility's design should enhance the environment for both the animals and the staff (see related box for important planning and design considerations).
Cats are one of the primary research animals for visual and auditory research2,3, as well as for other areas of neuroscience such as neuromuscular research4. Their large cognitive capacity makes cats valuable in neuroscience studies, but also mandates appropriate environments, with extra attention to providing adequate space, socialization, and physical enhancements.
Cats are social animals with a tendency to live in loose matrilineal groups, and they naturally groom and play with one another. Additionally, they are agile hunters–even in a laboratory environment, they must be able to climb, scratch, experience scents, scan their surroundings, and hide from other cats5. Cats generally respond to poor conditions by becoming inactive and exhibiting inhibition of behaviors such as self-maintenance (i.e., feeding, grooming, and elimination), exploration, or play6. This response is indicative of despondency and stress, which can skew data in certain types of studies. It is therefore necessary to examine natural cat behavior and develop enclosures that foster natural cat behaviors and minimize stress.
Benefits of Group Housing
Laboratory group housing benefits cats by encouraging normal behaviors, including socializing7 Since cat groups are matrilineal, it may be best to house several females with a few males (neutered, if required7). Neutered and intact males can live together; however, it is important to carefully determine if individuals are compatible. If the research permits cats to be housed together, and the cats are compatible, contact with conspecifics can be a valuable enrichment.
Colony housing is the preferred method of maintaining groups of cats, and cat colonies generally house two to six cats in one unit.
Important Considerations for Facility Planning, as per the Guide:
Gang housing is another option, whereby many cats are housed together in a large pen or room.
Space and Environment Requirements
The Guide recommends that cats less than or equal to 4 kg in weight have 3 ft2 of floor area per animal, and an enclosure height (from floor to top) of 24". Cats larger than 4 kg need at least 4 ft2of floor area and a height of 24". The Guide, however, notes that larger animals may require more space to meet performance standards5. A mother and litter can be housed comfortably in approximately 10 ft2 of cage space8.
The above are minimum requirements, however, and facilities must also bear in mind the behavior requirements of different cats. For example, cats of less than 3 kg are likely to be kittens or young, thus more active and playful than adults, and may therefore require more floor space than larger cats5.
Regardless of housing arrangements, environmental parameters (especially temperature and humidity) are also crucial to cats' health and well-being. Housing material and construction, along with numbers of animals per cage, are critical factors that affect cats' environmental temperatures. Recommended dry bulb temperatures for cats are 18-24C (64-84F)1; however, certain conditions, like post-operative recovery and housing young kittens away from their mothers, require raised temperatures. Humidity must also be kept between 30-70%1.
After satisfying basic space and environmental needs, suitable enrichments will vastly improve well-being, and decrease animal stress. In fact, cats actually benefit more from "enclosure complexities" than from simple increases in floor spaces. As the Universities Federation for Animal Welfare (UFAW) Handbook7 notes about cats, "Investing in the quality of the space rather than the quantity is often better value for the individual."
Cat Colony Units
Enclosures with Removable Dividers
One of the most popular arrangements for housing two to six cats is the cat colony unit–individual enclosures with removable doors or floors that facilitate flexible housing options and control access to socialization. If cats are compatible and the research permits group housing, for example, panels can be removed to allow cats to interact. If cats need to be housed individually (e.g.,post/preparturient females; mature males; sick, injured, or quarantined cats; or because of the research needs7), panels can be replaced to separate the animals. Table 1 lists contact information for some manufacturers who provide cat colony units. Enhancements to the units can also be added to augment cat enrichment (see below).
|TABLE 1. Contact information for cat housing manufacturers. Please note that this is a partial listing.|
Cedar River Laboratories
Lenderking Metal Products
LGL Animal Care Products, Inc.
Lock Solutions, Inc.
Suburban Surgical Co., Inc.
Allentown Caging (Allentown, NJ) cat housing units are available in configurations of two, four, or six cages. The four-cage unit and the six-cage unit, both composed of a standard 4 ft2 enclosure model (optional sizes available), have solid rear and right-side panels and optional divider panels between enclosures for socialization. In addition, Allentown Caging provides the Integral Cat Colony unit (55" wide x 30" deep x 75" high) for group housing. The removable divider grid assembly can configure single- and double- tiered compartments.
Four-cage (5.4 x 28" high) units with removable divider panels are available from Britz-Heidbrink (Wheatland, WY). When the panels that divide the two top or bottom cages are removed, a pair of cats (or mother and kitten) can be housed together in either the top or bottom section. Removing the litter pans between the top and bottom enclosures allows four adult animals to be housed together. All panel surfaces are made of a solid-surfaced, thermoneutral composite, which negates the heat-loss factor that animals experience when maintained on wire floors8. The Guide recommends keeping daily temperature fluctuations to a minimum to "avoid repeated large demands on the animals' metabolic and behavioral processes." Since it is key to prevent the animals from having to compensate for changes in their thermal environments, thermoneutral material is an important consideration.
Cedar River Laboratories (Mason City, IA) offers the VersaCageTM System Cat Condo (56" wide x 30" deep x 68" high) and the Mini Cat Condo (28" wide x 30" deep x 34" high), both featuring removable divider panels between enclosures that offer various configurations9.
Facilities can order custom-designed units for group housing from LGL Animal Care Products (Bryan, TX). LGL's past custom designs include a four-cage unit with removable side panels made from a section of clear plastic (to allow visual contact when closed) and a section of wire mesh (to allow olfactory contact when closed) . The unit also features removable floor panels for the top enclosures to allow full access to the unit.
Lab Products, Inc. (Seaford, DE) offers individual cat housing units with removable panels in four- or six-cage configurations. Enclosure sizes are 3 or 4 ft2 minimum with solid rear and right-side panels. Individual housing units can be configured two-over-two or three-over-three.
The ComfortCageTM from Lenderking Metal Products (Millersville, MD) consists of four units (25" wide x 25" deep x 26" high) stacked two-by-two with removable panels between adjacent units. The bottom of the enclosures is lined with an autoclavable, plastic insert for warmth and comfort. They also offer a group-housing unit (55" wide x 29" deep x 75" high) that features two levels with polypropylene resting boards, an access ramp, and an insertable litter box to separate the top and bottom levels.
Suburban Surgical, Inc. (Wheeling, IL) offers the stainless steel integral cat cage unit (6.4 ft2 x 79" high) featuring an insertable panel to divide the enclosure into two separate compartments.
Individual Enclosures for 2-3 Cats
Individual enclosures provide less variability with housing, but provide other benefits like sanitation and comfort. Lab Products offers large, self-contained stainless steel units for group housing, which measure 54.5" wide x 29" deep x 75" high. This unit does not have the option of separating the cats; instead, cats have access to all three levels in this unit, and experience a large amount of socialization. Lock Solutions (Laurence Harbor, NJ) customizes enclosures suitable for two to three cats. Plas-Labs, Inc. (Lansing, MI) provides autoclavable isolation units, suitable for two to three cats. The company claims the units are warm and soft, eliminating threats of hypothermia, and protecting animals from cross-contamination.
Stress in cats is negatively related to cortisol concentrations (as referenced in Rochlitz6) which can alter the scientific validity of studies. Cats are likely to become stressed when housed in a high-density environment, so facilities should design group-housing areas with adequate activity and provide hiding centers7 Small, high perches allow cats to be concealed yet able to monitor surroundings. Multiple level perches can provide a separate hiding place for each cat in the enclosure and a vantage point from which they can easily scan their surroundings in a relatively enclosed area. Cats also can remain clean by having a spot away from where they eat and eliminate wastes.
Most cat colony enclosures come with permanent resting shelves, although some have optional shelves that can be added. Allentown Caging and Lab Products offer three resting boards in one compartment; Allentown Caging resting boards are made from polypropylene. Britz-Heidbrink resting shelves are removable and made of interchangeable solid composite. They also offer a suspended, washable fleece hammock as an alternative to the standard shelf design. Cedar River Laboratories offers removable shelves, and two levels in the Mini Cat Condo. LGL Animal Care Products enclosures contain polyethylene or metal resting shelves, whereas Lenderking offers polypropylene resting boards, and Lock Solutions enclosures contain polypropylene resting shelves. Suburban Surgical offers shelves, in various materials, as optical accessories.
Rotating Food and Water Pans and Removable Litter Pans
Some companies offer removable food and water pans, or removable litter pans, to limit contact between caretakers and the animals and to facilitate cleaning. Allentown Caging units are equipped with 3"-deep, removable excreta pans and separate polycarbonite litter pans, and offer optional rotating food and water bowls. Britz-Heidbrink offers rotating feed and water bowls, and recessed litter pans for easy cleaning and sanitation. Cedar River Laboratories' Cat Condos contain two levels, so that food, water, and litter can be on one level, and, during removal, the cats are coaxed to stay on the other level. LGL Animal Care Products can customize enclosures to include rotating food and water feeders. Lab Products' individual units feature removable floor mesh and pans, and optional rotating or removable food and water bowls. The larger group unit also features a 4.1 "-deep, rolled-edge excreta tray. Lenderking offers removable food and water bowls and removable, autoclavable waste pans. Suburban Surgical offers watering systems and removable litter pans as optional accessories, and rotating food and water bowls as standard equipment. Their Angular Rack system allows easy cleaning of litter and the floor grid.
Although gang housing cats can be useful in some boarding and breeding scenarios, using pens or rooms to gang house cats is often not appropriate for a research setting. However, when the research being performed permits, a maximum of about 20-25 cats can be housed together in a laboratory setting5, depending on the available space.
Custom-designed enclosures are an option for gang housing and facilities with special needs. LGL Animal Care Products provides primarily custom-designed cat housing products for gang housing, including pens and individual enclosures. Recent projects include a fully equipped glass-paneled pen for 15-20 cats. Britz-Heidbrink also offers customized full-room enclosures with enrichment and activity devices.
Cats are likely to become stressed when housed in a high-density environment, so facilities should design gang-housing areas with adequate activity, and hiding centers must be provided7. Resting shelves are also important when gang housing cats, because they allow, for example, subordinate cats the opportunity to get away from more dominant cats in the gang. Some facilities have found that bookshelves or other pieces of furniture work well to enrich the environment in a gang-housing pen8 by acting as resting shelves.
While basic enclosure design can greatly improve the well-being of the cats used in research, the enrichments listed below are also very important to minimize cat distress.
The UFAW Handbook recommends adding windows to provide stimulation for cats7. Cedar River Laboratories offers VersaCageTM windows that can be used to overlook outdoor scanning areas (with enrichments like bird feeders or birdbaths), or an indoor scanning area to watch other cats, human activities, fish aquariums, caged birds, or televisions. Viewing windows can provide especially useful enrichment for individually housed cats. In addition, viewing windows also allow personnel to scan the animals with closed-circuit cameras.
Surfaces for Claw Abrasion
Surfaces types can be varied within the enclosure to encourage grooming and scratching. Scratch posts, rush matting, polyester fleece, wood, and carpet are all easy enrichments that encourage natural scratching. Britz-Heidbrink sells carpet inserts, called Scratcher Inserts, that are created to fit into Britz-Heidbrink enclosure systems.
Vertical Mobility Apparatuses
Cats are great climbers, and a variety of products maximize both vertical space and climbing exercise. Ladders, climbing frames, hammocks, and raised walkways increase vertical mobility. Allentown Caging sells a ramp assembly to allow cats to climb to multiple levels. Lab Products' mesh ramps make multiple levels accessible. Britz-Heidbrink offers extra perches and an innovative fleece hammock that cats can use both as a climbing device and as a place to sleep.
Because it is imperative for cats' well-being and for scientific validity to fulfill the Guide's recommendations, facilities must consider group housing whenever possible. When cat temperament and research design allow cats to be housed in groups, using cat colony units is most common. These units lend themselves to a great deal of flexibility, since animals can be kept apart or allowed to socialize with ease. However, facilities should also consider the pros and cons of using gang housing and individual enclosures. By housing cats in groups and with appropriate enrichments, according to their physical and psychological needs, researchers can decrease the animals' stress and distress.
Poe is Assistant Editor and Hope is Editorial Assistant of Lab Animal, 345 Park Ave. S., 10th Floor, New York, NY 10010-1707. Please send reprint requests to Poe at the above address.
1. Institute of Laboratory Animal Resources. Guide for the Care and Use of Laboratory Animals. National Research Council, National Academy Press, Washington, DC, 1996.
2. Javel, E., et al. Stochastic properties of cat auditory nerve responses to electric and acoustic stimuli and application to intensity discrimination. J. Acoust. Soc. Am.; 107(2):908-21, 2000.
3. Yoshimura, Y., et al. Properties of horizontal and vertical inputs to pyramidal cells in the superficial layers of the cat visual cortex. J. Neurosci.; 20(5):1931-40, 2000.
4. Perreault, M., et al. Depression of muscle and cutaneous afferent-evoked monosynaptic field potentials during fictive locomotion in the cat. J. Physiol.; 521 (Part 3):691-703,1999.
5. John Brautigam, personal correspondence.
6. Rochlitz, I. Recommendations for the housing and care of domestic cats in laboratories. Laboratory Animals; 34(1):1-9, 2000.
7. Poole, Trevor, ed. The UFAW Handbook on the Care and Management of Laboratory Animals, 7th Ed. Blackwell Science, Ltd., Oxford, England, p.445, 1999.
8. Gail Heidbrink, personal correspondence.
9. Dietrich, Bruce E. The VersaCage System. Veterinary Forum; p. 23, September 1997.
Reproduced with permission of the publisher. Published in Lab Animal Volume 29, No. 4, April 2000.