Facility Design and Management

General considerations in facility design

Layout and Contents

Calculation of space required

Support facilities

Space considerations for different species

Single vs. double corridors

Animal cubicles

Common errors

Temperature and humidity

Thermoneutral zones for different species

Metabolic rates and heat loss

Noise

Water

Water purification

Light

General features of animal holding areas{4099}

Since most institutions with animal research facilities receive public funds, most are bound by the "suggestions" of the Guide for the Care and Use of Laboratory Animals.{3948} These suggestions tend to dictate manufacturing standards; for example, the Guide suggests that in order to move equipment in and out of rooms, doors should measure 42 x 84", so manufacturers make all their equipment using those dimensions.

1. Environmental stability: temperatures held to within ±1°C and ±10% relative humidity, control of light and dark cycles with an accuracy of ±5 minutes, multiple light levels (i.e. so cleaning can be performed in brighter light such as 100 foot candles, and then dimmed for albino animals to perhaps 30 foot candles), HVAC design to minimize transmission of airborne particles and remove gaseous waste effectively (10-15 air changes per hour of 100% fresh air), and possibly the construction of small satellite barrier facilities to protect valuable genetic stocks.

2. Surfaces must be impervious to animal waste and cleaning liquids, impact-resistant and not slippery when wet.

3. Controlled access: to keep out unauthorized people, yet admit those who need to be there with reasonable convenience.

4. Flexibility to enable different species to be housed in each room.

Layout and Content of Animal Facilities

Methods of calculating space required{4099}

The amount of space required for animal facilities depends on the type of research being done in the building. One way to estimate the amount needed during planning is to calculate a percentage (usually 15-25%) of the total net square feet (nsf) of the laboratory space. The VA has estimated that this percentage increases as total nsf decreases. If there is less than 7,000 nsf of lab space, for example, 40% of it may need to be animal space. In facilities with more than 30,000 nsf of lab space, only 15% may need to be dedicated to the animal facility. A less popular method involves calculating the amount needed based on the number of scientists needing space. Formulas generally range between 400-500 nsf of animal facility space per faculty member using animals. 

If the species and approximate number of animals can be estimated, a more realistic calculation can be performed. Animal housing needs are estimated as follows:

For rodents, the floor space needed per rack ranges from 40-50 nsf per rack. Allow space for support inside the room such as change stations, animal procedure stations, sink, feed and sanitation equipment.

For animals housed in pens, the space needed for the pens themselves plus circulation space (i.e. a 24-sq. ft. pen may need 12 sq. ft. of circulation space around it). Remember to allow for canine exercise space. 

For NHPs, 1.5-2 times the floor space for the cage is reasonable for circulation. Psychological well-being needs must also be considered.

Support space needed is generally 40-60% of the total space, but is larger than the animal housing space. Again, the proportion depends on the total size of the facility. Surgery, veterinary care, X-ray, diagnostic lab and procedure rooms account for most of this space.

In institutions with a lengthy history of animal use, prior experience and the configuration of existing space are very useful guides when developing new spaces. Older facilities in general have insufficient support spaces, so be sure to plan these carefully.

Non-program space is used for circulation such as stairwells, corridors and elevators; mechanical chases, rooms and utility closets; and architectural space for walls and dead space. It is generally equal in size to the program space. For two buildings constructed at NIH, the end result was that the ratio of animal holding: support: non-program space was 30:40:50.

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Support facilities as suggested in the Guide{4099,3948}

1. Veterinary support facilities: offices, surgery suites, treatment and intensive care, necropsy, diagnostic laboratory, histopathology laboratory, hematology and chemistry laboratory, microbiology laboratory, and cold storage for dead animals.

2. Animal holding support facilities: a manager/secretary/records office, receiving and storage of animals and supplies, toilets/showers/lockers, lunch/break area, cagewash, cage repair, and diet preparation.

3. Research support facilities have increasingly been relocated to the animal facility in order to minimize transport in public areas, increase security, enhance animal health, and minimize potential experimental impact of moving animals.

Animal procedure rooms may be located near animal housing, or even provided as part of each animal room. Large facilities may require one shared procedure room for each 8-12 animal housing rooms. Performance of lengthy procedures within animal rooms is potentially distressful to the others and may impede sanitation. If procedures must be performed in animal rooms, design using a cubicle concept is preferable. Some options to consider in designing a new facility include traffic flow into the procedure rooms (i.e. whether entry is from a common corridor or through doors connecting the procedure room to the adjacent animal room), and whether procedure rooms might need to be converted to housing in the future (use the same construction materials for both).

Surgical suites for major survival surgery on nonrodent mammals must be performed in a dedicated room with appropriate ancillary support spaces to maintain an aseptic surgery. At a minimum, this would include a room for surgeon's preparation (dressing, scrubbing and gowning), a room for preparation and storage of sterile surgical instruments and supplies, and animal prep and recovery areas (which may share the same space if there are no problems with mixing species).

The operating room should have seamless conductive flooring with 4" coved base. Lighting should provide 125 foot-candles at 4' from the floor in addition to surgical lights. All outlets and the surgical lights should be on an emergency power system. Water-cooled laser units may require a source of water and a drain. Casework, if present, should be either recessed or flush-mounted and sealed around the junction with the wall to facilitate sanitation.

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Considerations for different species{4099}

Small rodents can be housed in rooms without floor drains. The ability to control lighting is important, i.e. to switch the day-night cycle to make it more convenient for researchers. Light levels of 15-30 foot candles are desirable for albino animals. Increasing the light to 100 foot candles may be desirable for cleaning; at UK the experience has been that this is not necessary and that staff frequently forget to turn off the higher-level lighting resulting in disruption for the animals. Noises that are intermittent, such as telephones, alarms, solenoids, and cage rack wheels should be minimized.

Larger rodents and rabbits make more of a mess in the room due to urine spraying; therefore the floors should be seamless and have floor drains to facilitate spray cleaning using a hose bib. Corrosion-resistant metals should be used on doors and frames.

Reptiles and amphibians do not require highly sophisticated construction. Standard gypsum wall board on walls and ceilings, and vinyl flooring may be adequate. Temperature should range between 20-29.5°C, humidity 33-60%. UV light is needed to provide vitamin D. In fish rooms, the floor needs to be impervious to water and made of non-slip material. On upper floors, weight of the water in the tanks should be considered during floor design. Ventilation should take the high humidity into account, and corrosion of metals is problematic.

Primates can be very noisy and very messy. A system for high-temperature spray washing is necessary, although this may be a mobile system. Walls and ceilings must be designed to handle the high-impact, high-humidity cleaning. Noise transmission should be minimized using sound baffles in ductwork, and avoiding back-to-back electrical boxes. Double-gating is important in rooms where animals may escape.

Dogs are also messy and noisy. Elevating the runs aids in sanitation. Noise abatement is important: a large dog can generate 120dB at 500 Hz. But acoustical abatement is challenging because of the need to sanitize materials. Surgical devocalization may be problematic. One interesting possibility is intermittent piping in of human voices and music, so that dogs do not bark every time a human enters the area.

Farm animals housed indoors need to have very durable walls and ceilings of sufficient height for those that may rear up. Floors must be non-slip and drains of adequate size to handle the loads. Stanchions or gates are necessary for safety reasons. 

Most farm species have 300° vision, but they have little binocular vision and consequently poor depth perception. In order to see things with depth, they lower their heads. Pigs and cattle will move toward lighter places without balking, something to keep in mind when unloading them at the loading dock. They have difficulty focusing on rail fences, so solid ones are better except if you want them to enter a gate, which should be open. They may balk if asked to move toward something that is moving or flapping. Cattle, pigs, sheep and goats have color vision, so handling facilities should be painted one color, as they may be likely to balk at sudden color changes. They are also very reluctant to enter a space that seems too small for them.

Cattle and sheep are more sensitive than humans to high-frequency noises. A loud ringing telephone can raise a calf's heart rate by 50-70 beats per minute. On the other hand, continuous low-level noise such as music can decrease the tendency for pigs to startle, and can increase weight gains.

Temple Grandin notes that livestock species have a "flight zone", a circular area within which intruders will cause them to flee. Chutes, pens and other environmental structures should be designed with this in mind.

The size of an animal's flight zone changes as they adapt to their environment; field animals have very large zones, whereas those living indoors have smaller ones approximating the dimensions of their pens. To get animals to move, enter the flight zone just at its edge where indicated above. To get them to move backwards, enter the zone ahead of the point of balance. Getting too close may cause the animal to turn back and run over the intruder. Cattle that are seen to rear in chutes often do so because someone is leaning over the fence too deeply into their flight zone; the best thing to do is back away from them to avoid injury and panic.

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The corridor system{4099}

Choices for corridors include single, double, or a combination. According to the Guide, corridors should be 7 feet wide and equipped with guardrails or bumpers and corner guards. Single-corridor systems have animal room doors that lead to a single corridor. Both dirty and clean materials share the same corridor. Dual-corridor systems ("clean/dirty corridors") have animal room doors leading to two separate corridors, one for clean materials and the other for dirty materials. The major consideration when deciding which system to use is the importance of controlling potential contamination. Movement of cages is the main focus to consider, since this is the most important activity in corridors. 

Managing the air balance is also critical to control airborne contaminants. Clean areas must be positive to dirty areas. Although facilities may be elaborately engineered to control air balance, in practical terms this is very difficult to maintain. Open doors, slipping fan belts and clogged filters can all ruin the air balance.

Although dual-corridor systems can in theory reduce the potential for cross-contamination, it may not control airborne contaminants very well. Dual-corridor systems require more space and more personnel management in order to work effectively. One might also consider adding interlocks, anterooms, cubicles, and/or ventilated racks.

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Cubicles{4099}

These are also referred to as "Illinois cubicles", "modified Horsfall cubicles", or "animal modules" and were first invented in 1961 by C.W. Doloway at the University of Illinois. Cubicles provide for more isolation of animals, but only hold one rack of animal cages. They work well in small facilities or those in which small groups must be isolated from others. The primary drawback is that when the doors are opened, the isolation effect goes away. Since air exchange must be high to control temperature load, however, airborne contamination of one cubicle by air from another may be minimal. 

Cubicles may be constructed from the same materials used in the room, i.e. concrete block, or they may be purchased ready-made, usually of stainless steel. Doors are often overhead-stacking, sash-type, with three leaves, that have counter-balance weights. They should be made of clear material to facilitate observation of the animals inside. Hinged doors are also used in some facilities. They may be easier to sanitize than the track-type sash doors which have many crevices for vermin to hide in.

Wall-mounted lights are used in cubicles because the rack fits so closely against the walls. Fluorescent lighting can be mounted vertically in the corners, along the back wall, or on the front behind the door frames. The lights should stop 18" above the floor.

Ventilation of cubicles is important to handle the heat load generated by the animals. One method is for air to enter in the aisle between cubicles, enter at the bottom of the cubicle doors and exit at the ceiling in the cubicles. Another method is to provide inlet air at the ceiling of each cubicle, and exhaust it near the floor of the cubicle. This is more expensive but may provide better containment of airborne contaminants, and the cubicles can be completely sealed to prevent escape of animals.

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Common design errors{4099}

Errors in planning facilities are to be avoided. Among these are:

Lack of coordination among the various building trades: this can result in doors not being big enough for equipment to go through, insufficient head room, not enough utilities to run the equipment, lack of shut-off valves and breakers that are accessible to users, filters that require shutdown to change, and insufficient protection of protruding items such as thermostats and door handles.

Problems with interior finishes: make sure the various layers (vapor barrier, membranes, substrates, prime coats and sealers) are all installed by the same company to ensure compatibility.

Vermin control, particularly cockroaches, is often inadequately designed. Joints and crevices must be kept to a minimum, and those that remain must be sealed.

Equipment selected must be adequate to handle to anticipated loads.

Fail-safe systems must be designed: dual-fan system on supply and exhaust air, dual filters so one can be changed while the other is still functional, dual chillers, emergency power to critical systems, alarms for system failures during normal hours and down time.

Security systems must be adequate. The perimeter must protect against intruders, individuals entering and exiting the facility must be adequately identified, and some animal rooms may need to be locked.

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Temperature and Humidity{4099}

Thermoneutral Zones

gMacaca 25-31

Source: Modified from Besch (1985). Reprinted with permission of the American Physiological Society.{4099}

When animals are housed at 20-30°C and 40-60% relative humidity, they adjust to their environment using behavioral means such as burrowing in the bedding or huddling together. Mice housed singly consume 30% more food than those housed in groups of five. Even social factors can affect heat production: dogs housed in isolation dissipate more heat than those housed with visual or aural contact.

Animals respond differently to temporary changes in their environmental temperature. The response of the animal depends in part on the temperatures in which it was raised. Mice cannot tolerate elevated temperatures (44°C) for more than 26 minutes; however, rats and hamsters tolerate 50°C for 39 and 27 minutes. Guinea pigs have greater high temperature tolerance than rats.

Relative humidity is the comparison of the weight of water vapor in a unit volume of air to the weight of water vapor in the same volume of saturated air. It is important in animal rooms because it affects the rate of heat loss from the animals. As air temperature rises to 37°C, evaporation becomes the only effective cooling mechanism, but if the relative humidity is very high this mechanism fails to work. The design process must take into account changes in relative humidity caused by the use of the room, temporary cleaning water loads, thermal and mass loads of the animals, cleaning equipment, lights, and the presence of people.

Low relative humidity has been associated with increased dust and respiratory infections, and ringtail in mice, rats and hamsters. High humidity may reduce resistance to infections.

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Metabolic size and heat ratios

In trying to find a common unit to express the metabolic rate of animals of all sizes, Kleiber deduced that body surface area was too ill-defined. Metabolic rate per unit of surface area is higher for larger animals. However, the mass of an animal raised to the ¾ power was useful; fasting homeotherms of any size produce 70kcal/kg^¾ per day. 

The metabolic heat ratio (MHR) of an animal is the ratio of its metabolic rate when measured under steady-state conditions to the standard metabolic rate given above. An animal of any species has approximately twice the heat dissipation when living in a cage than when under basal conditions, as shown by the three lines in the graph below. This varies tremendously, and some estimates are that during a normal day, an animal's MHR varies from 1-10.

To estimate the heat gain in order to design HVAC systems, the following equations apply:

ATHG=2.5M

M=3.39BW^¾ 

where ATHG = average total heat gain in watts/animal

M=metabolic rate in watts/animal

BW=body weight in kg

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Noise {4099}

The decibel is the log of the ratio between the pressure exerted by an airwave and a reference pressure (20 µPascals); this is done so that 0 decibels is the approximate threshold of human hearing. Frequency is measured in Hertz, which is cycles per second. Human hearing is fairly insensitive to low-frequency sounds, so that these must be of higher amplitude in order to be heard. Decibel meters are usually fitted with a filter network to account for human hearing called A weighting. Sound level meters, therefore, read out in units indicated as dBA. Rats are even less sensitive to low-frequency sounds than humans. Cats are known to have similar responses as humans to sounds <500Hz, but above this frequency cats are more sensitive than humans. The same is true of most small laboratory mammals, indicating that there should be concern for high-frequency noise in animal facilities.

Noise control (NC) curves have been developed to describe acceptable noise levels in human environments. The noise spectrum is divided into eight equal octave bands. Each NC curve defines the highest sound level in dB for each octave band that is acceptable for a particular space. As the frequency of the sound increases, the acceptable decibel level decreases.

When considering noise abatement, consider the source of the noise, the path it travels, and the receiver. It should be obvious that during planning, areas where noise would be objectionable should be placed as far as possible from areas that generate noise. Keeping animal housing far from the laboratory, however, increases animal travel distance. A buffer zone, even a corridor or storage room, can be an effective way to manage this.

Barriers can be placed between the source and the receiver, but must be planned in conjunction with an acoustical professional. In general, the height of the barrier and the distance from the source and receiver are used to design good sound protection. The barrier should be as close as possible to the source, so that it throws a large "acoustical shadow". It should be at least 2 feet above the line of sight between the source and the receiver. Reducing noise by 8-12dB is perceived as reducing the noise to about half. Openings in the barrier (i.e. a gate in a wood fence) limit its effectiveness dramatically. Wall perimeters should be caulked completely; outlet boxes should not be placed back-to-back. Doors should be as massive as possible and have good perimeter gaskets. At the bottom of a door, there should be a drop seal.

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Water {4099}

Watering systems

Sometimes water is provided in bottles, which are filled using a mechanized bottle filler. A proportioner may be included to add acid, chlorine or even medication to the water as the bottles are filled. For non-specific animal husbandry, automatic watering systems should be considered to save on labor and decrease contamination.

The most common water distribution system is called a room distribution flush system. Water is provided to all the rooms, and at the end of the road there is a method of flushing the pipes. The volume of water contained in the distribution system is almost always more than the animals themselves drink daily. Flushing improves water quality at the point of use, the rack manifold. Pressure stations on the front end can be equipped with sensors to alert the user to possible leaks or pressure failures.

In a recirculating room distribution system, water is constantly recirculated to prevent stagnation and potentially decrease microbial growth. The system may recirculate water within a single room or a group of rooms. Flow control units are located at the terminal point in the room, and maintain recirculation at 18-20 gph.  The holding tank should contain the minimum amount of recirculated water to provide reserve in case of supply interruption. It should be drained periodically when the animal population drops. An important component of this type of system is an ultraviolet lamp to clean the water. One alternative to this system is to recirculate water only to the level of the pressure reducing station for each room. This means that water that has passed the animal lixits doesn't get recirculated, so there is no need to periodically drain the holding tank. Each room is flushed periodically to clean the lines there.

In each type of automated system, the terminus is the room distribution piping and the recoil hoses. The piping is attached to the walls with stand-off brackets, which keep the pipe ¼-½" from the wall to prevent vermin from hiding there. 

Manifolds in cage racks are of several different configurations and vary in cost. The best is a "reverse S" type in which water goes to the bottom of the manifold and then proceeds upward in an S configuration to each row, with a vent at the terminus on top of the manifold. This prevents air bubbles from becoming trapped in the manifold which could keep animals from receiving water. 

The manifold should be sanitized by filling with chlorinated water and then flushing thoroughly (20-25 gpm). A portable sanitizer can be used to sanitize the pressure reducing stations and room piping.

Reactive or aggressive water, such as RO water, can eventually dissolve brass, bronze and copper. Stainless steel or chlorinated polyvinyl chloride (CPVC) pipe are better choices. 

For a discussion of methods of water filtration, click here.

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Light{4099}

Nocturnal laboratory animals, particularly albinos, do not need bright lighting. Light levels of 30-50 foot-candles 30" above the floor should be sufficient. Primates, however, should have both a brighter light and a broader spectral range of light. Fluorescent lights with a chromaticity of 5000°K is close to natural light. It is suggested that all animal rooms have separate switching that enables care personnel to increase the light level to 100 foot-candles to facilitate cleaning, observation and experimental work.

Since nobody understands how the human eye sees color or interprets it, there are several relatively unsatisfactory methods to describe the colors of light bulbs. The only internationally agreed-upon color rendering system is the color rendering index (CRI). It is a graphical comparison of how a light source shifts the location on a color triangle compared to a reference source of the same chromaticity. For chromaticities of 2000-5000K, the reference source is a black body radiator (a piece of metal that, as it is heated up, changes color from red to yellow to white to blue-white); for chromaticities above 5000K the reference is a form of daylight. If the two look the same, the CRI is 100. An incandescent lamp and outdoor north sky daylight both have a CRI of 100. CRI is still imperfect, because our perception of color under lights with the same CRI will be very different. CRI is only an indicator of the relative color-rendering ability of a light source.

Where color rendition is critical, such as exam rooms, surgery, and necropsy, use high-CRI continuous-spectrum sources such as Deluxe Cool White (CWX), Chroma 50 (C50), or Chroma 75 (C75). 

Where both color and lighting level are important, use either SP30, SP35, or SP41 General Electric Specification Series Color lamps, with three-peak rare earth phosphors. Specification Series colors look more colorful because of the three-peak phosphors; however, they do not increase the contrast of black and white and may not be useful in the office.

©1999, Janet Becker Rodgers, DVM, MS, DipACLAM, MRCVS

All rights reserved.

Comments? Send an email to janet.rodgers@vet.ox.ac.uk