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Suggested Citation:"Session 4: Environmental Control for Animal Housing." National Research Council. 2004. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington, DC: The National Academies Press. doi: 10.17226/11138.
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Session 4
Environmental Control for Animal Housing

Suggested Citation:"Session 4: Environmental Control for Animal Housing." National Research Council. 2004. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington, DC: The National Academies Press. doi: 10.17226/11138.
×

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Suggested Citation:"Session 4: Environmental Control for Animal Housing." National Research Council. 2004. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington, DC: The National Academies Press. doi: 10.17226/11138.
×

Environmental Controls (US Guidance)

Bernard Blazewicz and Dan Frasier

CURRENT US GUIDANCE

Current guidance regarding environmental conditions for vivariums is primarily found in industry and government publications. The most widely accepted publication and the primary reference on animal care and use is the Guide for the Care and Use of Laboratory Animals (the Guide), published by the National Research Council (NRC 1996). Other pertinent references include the American Society of Heating, Refrigeration, and Air-Conditioning Engineers (ASHRAE 2003), the National Institutes of Health Design Policy and Guidelines (NIH 1999), the Biosafety in Microbiological and Biomedical Laboratories (CDC/NIH 1999), and the US Department of Agriculture ARS 242.1M (USDA 2002).

The Guide places emphasis on performance standards, as opposed to engineering standards, for environmental control. Performance standards are viewed to be more flexible and more concerned with the outcomes than engineering criteria.

To apply the Guide effectively, a team approach is recommended whereby facility users and designers can share expertise to meet desired outcomes. The Guide is not a how-to-build handbook on vivarium design; it provides broad recommendations for environmental conditions that have proven to work well. Individuals responsible for well-designed facilities begin with a thorough understanding of the scientific needs, and

Suggested Citation:"Session 4: Environmental Control for Animal Housing." National Research Council. 2004. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington, DC: The National Academies Press. doi: 10.17226/11138.
×

then translate that information into a facility that meets the expectations of the users.

The Guide allows for interpretation or modification in the event that acceptable alternative methods are available, or unusual circumstances arise when deviating from the Guide. For example, ventilation rates that exceed 10 to 15 air changes per hour (ac/h) would be allowable, given appropriate justification. When deviating from the Guide, thought should be given to other environmental factors that may be affected by the deviation. In the case of air change rates, it is possible that air movement, diffusion pattern influence on the animal’s microenvironment, and the relation of the type and location of supply-air diffusers and exhaust vents would warrant further consideration.

ENVIRONMENTAL CRITERIA

Environmental criteria topics that have been discussed include the following: temperature and humidity, ventilation rate, lighting, containment, and air quality. Each of these topics is briefly described below.

Temperature and Humidity

The most common source of data for temperature and humidity is ASHRAE; however, most data are outdated and date back to the 1950s or 1960s. Some researchers believe that the measurements concluded from past heat and moisture data are too low for today’s animals. Recent rodent data have provided evidence that rodents have higher metabolisms and heat generation (Riskowski and Mermazedeh 2000).

Ventilation Rate

Ventilation rates have historically followed the 10 to 15 ac/h (fresh air) recommendation from the Guide. This range has proven to be a good range although different approaches allow lower ventilation rates while maintaining a stable animal room environment (i.e., ventilated caging systems). Some applications, species, and rooms require more than 15 ac/h. It should be emphasized that 10 to 15 ac/h has historically proven successful in managing most animal thermal and respiration loads and equipment loads. However, the Guide is clear that calculations must be performed to determine the air change rates required to remove the thermal and moisture loads and provide any additional make-up air exhaust devices (i.e., fume hoods or biosafety cabinets).

Suggested Citation:"Session 4: Environmental Control for Animal Housing." National Research Council. 2004. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington, DC: The National Academies Press. doi: 10.17226/11138.
×
Lighting

Lighting normally consists of dual levels (day/night) and override for cleaning. Present methods of monitoring and controlling lighting are to use the building automation or environmental monitoring systems. Typical ranges applied are 30 foot-candles (f.c.) for day, 0 f.c. for night. Lighting levels for cleaning range from 70 to 100 f.c. for 1 hour.

Containment

Reduction of cross-contamination between holding rooms is normally accomplished through pressurization—supply/exhausting air to/from the room to direct air in or out of the room. Quarantine, isolation, biohazards, and nonhuman primates should be kept under negative pressure. Pathogen-free animals, surgery, and cleaning and equipment storage should be kept under positive pressure. The bubble diagram in Figure 1 is an illustration of different types of pressure schemes that can be found in a vivarium.

FIGURE 1 Example of the different types of pressure schemes in an animal research laboratory vivarium.

Suggested Citation:"Session 4: Environmental Control for Animal Housing." National Research Council. 2004. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington, DC: The National Academies Press. doi: 10.17226/11138.
×
Air Quality

Current guidelines provide no criteria to judge air quality. Past practices have included the use of high-efficiency particulate air (HEPA) filters. The Guide recommends HEPA filters for certain areas—surgery and post-operative holding rooms. Heating, ventilation, and air-conditioning (HVAC) systems normally use ASHRAE-rated filters, which are effective at keeping HVAC system components clean and extend the life of HEPA filters.

TECHNOLOGICAL ADVANCES

Recently, a greater focus has been placed on the room environment, which includes room allergen levels, the migration of airborne pathogens, temperature/humidity comfort levels, and biosafety containment. Animal facilities are now utilizing a more comprehensive and scientific approach to address these concerns. The analytical tool of choice to aid in the design of these rooms is computational fluid dynamics (CFD). CFD has been used successfully over the past 20 years for accurate modeling of air currents, temperature, and humidity levels. The method is further evolving to include fresh air dwell times, particulate movement, stagnation, and projected odor levels. Other parameters that may be studied include inlet diffuser type, animal heat loads, cage/rack placement, and exhaust air systems placement. CFD provides a visual representation of the effects of airflow in the holding room and a better understanding of the room dynamics. Together, these advances provide better scientific data for the development of future guidelines. Figure 2 is an illustration of a sample of CFD output that was used to determine odor migration in a canine holding room, modeling several different versions of supply/ exhaust placement, to determine which arrangement provided better containment of odor (AALAS 2003).

GAPS IN CURRENT GUIDANCE AND CRITERIA

Noise and Vibration

Currently, there is no acoustical criterion for animal rooms contained in the Guide or from ASHRAE. The hearing ranges of animals are different from humans, and the ranges are different among species. Examples of ranges are shown in Figure 3.

Limited published data are available on sound sources and mitigation techniques. Numerous internal studies have been performed, and techniques and strategies have been developed to mitigate noise, which

Suggested Citation:"Session 4: Environmental Control for Animal Housing." National Research Council. 2004. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington, DC: The National Academies Press. doi: 10.17226/11138.
×

FIGURE 2 Computational fluid dynamics (CFD) analysis of a canine holding room. CFD was used to develop a three-dimensional model of a gas concentration in a room at the prescribed concentration level of 5 ppm. End view, NH3 isosurfaces measuring 5 ppm.

FIGURE 3 Examples of differences among the hearing ranges of humans and various animal species. Modified from Warfield (1973) and Sales and Pye (1974).

Suggested Citation:"Session 4: Environmental Control for Animal Housing." National Research Council. 2004. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington, DC: The National Academies Press. doi: 10.17226/11138.
×

can be helpful in developing criteria for future updates to current guidelines. Published vibration criteria for animal facilities are also very limited, but again, numerous internal studies have been performed that could help the industry establish such criteria.

Performance Standard for Ventilated Cages

Ventilated caging systems have evolved into many different airflow strategies based on the work of various manufacturers. Generally, manufacturers have worked closely with animal research professionals to develop caging systems that have well-founded concepts. It is recommended that the scientific community, along with industry professionals and manufacturers, develop a performance standard for ventilated cages to identify the knowledge base and the most important criteria.

SUMMARY

  • Established guidelines have proven to work well but have not been updated to reflect new trends in vivarium research that affect the environment.

  • Technology has advanced our understanding of the macro- and micro-environment.

  • Independent research and testing have produced new insights that have affected the vivarium environment.

  • Additional guidance and work are required to close the gaps.

  • Variances based on scientific data are recognized and allowed in the Guide.

RECOMMENDATIONS

  • Update ASHRAE guidance based on current research.

  • Update the Guide to include criteria for noise and vibration.

  • Develop a performance standard for ventilated cages.

  • Provide guidance to industry in a new facility design guide that can incorporate technological advances and current practices.

REFERENCES

AALAS [American Association of Laboratory Animal Science]. 2003. Evaluating odor migration in a new kennel project using CFD analysis. Poster presentation at the October 2003 meeting of the American Association for Laboratory Animal Science held in Seattle, Washington.

ASHRAE [American Society of Heating, Refrigerating and Air-Conditioning Engineers]. 2003. HVAC applications. In: ASHRAE Handbook. Atlanta, GA.

Suggested Citation:"Session 4: Environmental Control for Animal Housing." National Research Council. 2004. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington, DC: The National Academies Press. doi: 10.17226/11138.
×

CDC [Centers for Disease Control and Prevention]. 1999. Biosafety in Microbiological and Biomedical Laboratories. Atlanta, GA: CDC.


NIH [National Institutes of Health]. 1999. NIH Design Policy and Guidelines. Bethesda, MD: NIH.

NRC [National Research Council]. 1996. Guide for the Care and Use of Laboratory Animals. 7th ed. Washington, D.C.: National Academy Press.


Riskowski, G.L., and F. Memarzadeh. 2000. Investigation of statis microisolators in wind tunnel tests and validation of CFD cage model. ASHRAE Trans 106:867-876.

Ruys, T., ed. 1991. Handbook of Facilities Planning. Vol 2. Laboratory Animal Facilities. New York: Van Nostrand Reinhold.


Sales, G., and D. Pye. 1974. Ultrasonic Communication by Animals. London: Chapman & Hall.


UFAW [Universities Federation for Animal Welfare]. 1996. Noise in Dog Kennnelling: A Survey of Noise Levels and the Causes of Noise in Animal Shelters, Training Establishments, and Research Institutions. Herts, UK: UFAW.

USDA [US Department of Agriculture]. 2002. ARS 242.1M. Washington, DC: Agricultural Research Service of USDA.


Warfield, D. 1973. The study of hearing in animals. In: Gay, W., ed. Methods of Animal Experimentation. London: Academic Press. p. 43-143.

Suggested Citation:"Session 4: Environmental Control for Animal Housing." National Research Council. 2004. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington, DC: The National Academies Press. doi: 10.17226/11138.
×

European Guidelines for Environmental Control in Laboratory Animal Facilities

Harry J. M. Blom

Like farm animals and pets, laboratory animals were originally derived from wild living ancestors. The early scientists started to house and breed those animal species, mainly mammals, which were easiest to maintain under artificial conditions in terms of economics and animal needs. Of course, other criteria also played an important role in the selection process. The species of choice needed to be accurate models for biomedical research, the results of which were to be extrapolated to humans. Further easy breeding, a short life cycle, and large numbers of offspring were preferred—arguments that resulted in the use of rodents for experimental purposes. However, when introduced in the laboratory, the animals had to go through a process of habituation to the artificial housing conditions that far from resembled the animal’s natural living environment. Animal enclosures in the modern animal facility are of a much better quality, and conditions are adequately controlled. Still, animals may be unable to adapt to these housing conditions and consequently may develop abnormal behavior, stress, affected physiology, and/or mental state. Therefore it is essential to define standards for housing conditions that meet the animals’ requirements. Preferably these standards should be based on scientific data. Prevailing expert views and daily practice are to be considered acceptable when scientific data are not available.

The aim of international regulations for the care and use of laboratory animals is to enhance animal welfare, to set standards, to harmonize procedures, and to safeguard the quality of biomedical research. The Euro-

Suggested Citation:"Session 4: Environmental Control for Animal Housing." National Research Council. 2004. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington, DC: The National Academies Press. doi: 10.17226/11138.
×

pean regulations for the protection of animals used for experimental and other scientific purposes are based on both scientific results and common sense. Directive 86/609/EEC provides mandatory guidelines for the 15 nations that are joined in the European Union. Convention ETS 123 has been set up by the 45 member states of the Council of Europe. The content of the Convention is mandatory in those member states that have signed and ratified this document. In both cases, the national authorities are obliged to transpose and implement the European regulations into national law. At this time, Appendix A to Convention ETS 123, providing guidelines for the housing and care of laboratory animals, as well as the European Directive are being revised. Other authors in these proceedings will elaborate on both revision processes. The focus of this presentation is on the new content of Appendix A.

After a special workshop in Berlin, Germany, in 1995, a Multilateral Consultation in 1997, and seven consecutive 3-day Working Party meetings in the period 1999-2003 at the Council of Europe in Strasbourg, France, discussion has been finalized for the General Part of Appendix A and for the species-specific sections for rodents and rabbits, dogs, cats, ferrets, nonhuman primates, and amphibians. It is anticipated that discussion on the sections for farm animals, birds, reptiles, and fish can be closed during the next meeting in early June 2004. Late in 2004, a Multilateral Consultation should conclude the revision process. The documents that are still under debate are restricted. The information presented herein is therefore limited to the finalized sections.

With respect to environmental conditions, the General Part contains provisions that are universally applicable to all laboratory animal species (Table 1). Where appropriate, the species-specific sections provide detailed guidelines, values, or ranges to meet the particular needs of the species concerned (Table 2). All provisions apply to inside enclosures. Where animals have access to outside enclosures, it is strongly recommended to prevent prolonged exposure to extreme climate conditions such as heat, frost, bright sunlight, or heavy rainfall. Although some species may tolerate such weather conditions relatively well, the animals should always have the ability to make a free choice to go inside or seek shelter.

As mentioned, the new sections in the revised Appendix A are based on scientific results. Unfortunately the availability of such data is limited. Thus, where science could not support the discussions during the Working Party meetings, there was no other option than to rely on expert views and common sense—a procedure that is fully justifiable but that emphasizes at the same time the need for further research into the tuning of housing conditions in the laboratory with the needs of the animals living in this artificial environment. The main problem to be solved is to generate

Suggested Citation:"Session 4: Environmental Control for Animal Housing." National Research Council. 2004. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington, DC: The National Academies Press. doi: 10.17226/11138.
×

TABLE 1 Provisions on Environmental Conditions in the General Part of Appendix A to Council of Europe Convention ETS 123

Ventilation

Should:

—Satisfy the requirements of the animals

—Provide sufficient fresh air of appropriate quality

—Be 15-20 changes/hr

—Remove excess heat and humidity

—Prevent spread of odors, noxious gases, dust, and infectious agents

 

Recirculation of untreated air should be prevented

 

Draft and noise disturbance should be avoided

Temperature

May affect metabolism and behavior of the animals

 

Should be precisely controlled (heat/cool) and measured and logged daily

 

Newborn, hairless, ill, and newly operated animals need special attention

Humidity

May need to be controlled within a narrow range to minimize the possibility of health or welfare problems

 

Should be recorded and logged daily

Lighting

Should satisfy biological requirements

 

Should provide a satisfactory working environment

 

Exposure to bright light should be avoided, and darker areas should be available

 

Regular photoperiods should be provided

 

Interruptions of the photoperiod should be avoided

Noise

High noise levels and sudden loud noises may cause stress

 

Ultrasounds should be minimized particularly during the resting phase

 

Holding rooms should be provided with noise insulation and absorption materials

funding for these refinement studies. Furthermore, the classical approach of looking for signs of distress and/or discomfort evoked by imperfect housing conditions could be supplemented by studying expressions of pleasant experience. Predictability and controllability of the environment can be very rewarding to the animals and may therefore be expected to contribute to the well-being of captive living animals.

Suggested Citation:"Session 4: Environmental Control for Animal Housing." National Research Council. 2004. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington, DC: The National Academies Press. doi: 10.17226/11138.
×

TABLE 2 Provisions on Environmental Conditions in the Species-Specific Sections of Appendix A to Council of Europe Convention ETS 123

 

Temperature

Humidity

Lighting

Noise

Rodents

 

  • 20-24°C (+6°C in cage)

  • Provide opportunity to control microclimate

 

  • 55±10%

  • Gerbils 45±10%

 

  • Low light levels in the cage

  • Albino’s < 65 lux

  • Red light can be used for monitoring rodents in their active phase

 

  • Are in particular very sensitive to ultrasound

  • Ultrasound may affect prenatal development

  • Sudden loud noises may cause audiogenic seizures

Rabbits

 

  • 15-21°C (+6°C in cage)

  • Provide opportunity to control microclimate

 

  • Not less than 45%

 

 

  • Are in particular very ultrasound sensitive to

  • Ultrasound may affect prenatal development

  • Sudden loud noises may cause audiogenic seizures

Dogs

 

  • 15-21ºC when precise control is required during procedures

  • Otherwise a wider range provided that welfare is not compromised

 

  • Control unnecessary

  • Can be exposed to wide fluctuations of ambient relative humidity without adverse effects

 

  • Duration of the light period should be at least 10-12 hr

  • Low-level night lighting (5-10 lux) should be provided to avoid startle reflex

 

  • Noise in dog kennels can reach high levels that can cause damage to humans and that could affect the dogs’ health and physiology

  • By addressing the dogs’ behavioral needs, barking may be decreased

Suggested Citation:"Session 4: Environmental Control for Animal Housing." National Research Council. 2004. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington, DC: The National Academies Press. doi: 10.17226/11138.
×

 

Temperature

Humidity

Lighting

Noise

Cats

 

  • 15-21ºC when precise control is required during procedures

  • Otherwise a wider range provided that welfare is not compromised

 

  • Control unnecessary

  • Can be exposed to wide fluctuations of ambient relative humidity without adverse effects

 

  • Duration of the light period should be at least 10-12 hr

  • Low-level night lighting (5-10 lux) should be provided to avoid startle reflex

  • Light sources may be perceived as flickering because of the cats’ high critical fusion frequency

 

  • Unpredictable noise may cause stress

Ferrets

 

  • 15-24ºC

  • Absence of welldeveloped sweat glands may lead to risk of heat exhaustion when exposed to high temperatures

 

  • Control unnecessary

  • Can be exposed to wide fluctuations of ambient relative humidity without adverse effects

 

  • Duration of the light period may vary between 8-16 hr

  • Modification of the photoperiod is an important tool for the manipulation of the reproductive cycle

 

  • Lack of sound or auditory stimulation can be detrimental and make ferrets nervous

  • Loud unfamiliar noise and vibration have been reported to cause stress-related disorders

Suggested Citation:"Session 4: Environmental Control for Animal Housing." National Research Council. 2004. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington, DC: The National Academies Press. doi: 10.17226/11138.
×

 

Temperature

Humidity

Lighting

Noise

Nonhuman Primates

 

 

 

 

 

  • Marmosets and Tamarins

 

  • 23-28ºC but slightly higher levels are acceptable

 

  • 40-70% but levels higher than 70% will be tolerated

 

  • Not less than 12 hr of light

  • Provision of a shaded area

 

  • Exposure to ultrasound should be minimized

 

  • Squirrel Monkeys

 

  • 23-28ºC without abrupt temperature variations

 

  • 40-70%

 

  • Not less than 8 hr of light

  • Light spectrum should resemble daylight, i.e. including UV light

 

 

  • Macaques and Vervets

 

  • 16-25ºC is suitable

  • 21-28ºC is more suitable for long-tailed macaques

 

  • 40-70%

 

  • 12:12 light/dark cycle

 

 

  • Baboons

 

  • 16-28°C is suitable

 

 

 

Suggested Citation:"Session 4: Environmental Control for Animal Housing." National Research Council. 2004. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington, DC: The National Academies Press. doi: 10.17226/11138.
×

 

Temperature

Humidity

Lighting

Noise

Amphibians

 

  • Amphibians are ectothermic

  • Areas of different temperatures are beneficial

  • Exposure to frequent fluctuations in temperature should be avoided

 

  • A hydrated integument and the possibility to take up moisture through the skin are essential

 

  • Photoperiods and light intensities should be consistent with the natural conditions

 

  • Noise, vibration, and unexpected stimuli should be minimized

 

  • Aquatic urodeles

 

  • 15-22°C

 

  • 100%

 

 

 

  • Aquatic anurans

 

  • 18-20°C

 

  • 100%

 

 

 

  • Semiaquatic anurans

 

  • 8-10°C

 

  • 50-80%

 

 

 

  • Semiterrestrial

 

  • 23-27°C

 

  • 80% anurans

 

 

 

  • Arboreal anurans

 

  • 18-25°C

 

  • 50-70%

 

 

NOTE: For ventilation the provisions in the General Part apply to all species. The same applies for empty cells in the table.

Suggested Citation:"Session 4: Environmental Control for Animal Housing." National Research Council. 2004. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington, DC: The National Academies Press. doi: 10.17226/11138.
×

Breakout Session: Lighting

Leader: Harry J. M. Blom

Rapporteur: Michael K. Stoskopf

The session leader posed the following questions to the group:

What is the scientific basis or peer-reviewed literature for housing standards for laboratory animals? What other (if any) influences or factors are involved?

General consensus was quickly reached among the participants that the scientific basis for housing standards for laboratory animals is uneven, with large areas that lack adequate investigation. Some concern was expressed that not all “scientific” information is sufficient for development of standards. Participants stressed the care in design and execution of experiments, including the need for replication and proper controls necessary to provide reliable information. In addition, scientific design and replication of studies varies: One poorly designed study can dictate standards inappropriately.

The moderator posited that the influences on standards, other than peer-reviewed scientific data, include daily practice, common sense, and prevailing expert views. It was suggested that it might be appropriate to establish standards. The group allowed that although these factors do become the basis of standards, there are important concerns with this approach, and the development of standards without scientific basis is fraught with the peril of inappropriate regulation. These concerns were expressed first in a question related to expertise and second in the subsequent brief discussion of common sense.

Suggested Citation:"Session 4: Environmental Control for Animal Housing." National Research Council. 2004. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington, DC: The National Academies Press. doi: 10.17226/11138.
×

Who determines the prevailing expert view?

Participants indicated that individuals with different backgrounds can have diametrically opposed biases on appropriate prioritization of the various concerns. In addition, they felt that giving unfounded dogma official sanction can retard proper scientific examination of the viewpoint. Similarly, some expressed the opinion that common sense can frequently be wrong. Individuals may tend to express anthropomorphic views basing judgment of other species, needs on human senses and needs, and this may not always be appropriate.

Although it is necessary to have some basis for a starting point, participants felt it would be optimal if the starting point were based on scientific evidence.

Where are the gaps in our scientific knowledge? Is the information missing? Is it outdated?

Discussion of these questions was divided into three areas related to light: (1) intensity, (2) periodicity, and (3) transitions, including “flicker detection.”

INTENSITY

Issues related to light intensity were organized into the following three categories for discussion: (1) satisfaction of biological requirements, (2) safety and efficiency of people working in the room, and (3) effects of excessive exposure. All three areas have gaps in knowledge.

Biological requirements related to vitamin synthesis have been determined for some species; however, less is known about intensity requirements relative to neuroendocrine function, especially across a broadly comparative group of laboratory species. The safety and efficiency of people working in the room have been studied more than the preceding category, but often in studies unrelated to laboratory animal care. Human effectiveness and its variability under different lighting conditions are relatively well studied. Much of the discussion focused on the issue of effects of exposure to excessive intensity, with particular focus on light that is too bright and causes blindness or retinal lesions in some species. Very bright light should be avoided for some species (e.g., albino rodents, as recommended in the Guide reference to 30 to 50 foot-candles), and darker areas should be available to the animals. With regard to the needs of other strains and species, participants stated that tiered cages and the location in the tier are factors that have not been considered, because most studies have looked at average room conditions.

Some time during this session was devoted to determining how dif-

Suggested Citation:"Session 4: Environmental Control for Animal Housing." National Research Council. 2004. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington, DC: The National Academies Press. doi: 10.17226/11138.
×

ferent institutions are dealing with light intensity challenges. Mentioned were manufactured lenses covering fluorescent bulbs to reduce lighting to within range; removal of some of the bulbs commonly used for lights in ceiling, but not with uncovered tops on racks; and the practice of rearing animals in the dark (e.g., use of transgenics) in ophthalmology studies. Participants expressed concerns regarding potential damage caused by light intensity that is too low (e.g., on the retina).

PERIODICITY

Dr. Blom suggested starting with the following areas, in which the knowledge base is well established:

  • Providing regular photoperiods;

  • Avoiding interruptions of those periods;

  • Considering low-level night lighting; and the

  • Potential importance of the duration of the light/dark cycle, for the manipulation of reproductive cycles in breeding and related research.

The group did not take exception to those points, but discussed that periodicity and particularly the duration of light/dark cycles is important for many other things besides reproduction.

Much of the discussion centered on experiences with nocturnal animals such as owl monkeys. There is still more to be understood about the use of simulated moonlight (lower intensity vs. spectral shifts) across species. Simulated moon light is being practiced in some of the forms, but has proven impractical for allowing workers to properly clean and manage rooms and adaptation to the low levels (about 10 lux), For this reason, it does not appear to be effective. The main solution to the problem created by workers being required to turn on the lights appears to be creative shifts of time reversal so that “daylight” exposures occur during working and cleaning, and “dark” periods are reserved for observation periods.

The important point was stressed that this issue is more refined than simply identifying the light/dark cycle. The cycle can affect results for many types of studies such as metabolism, for which considerable data exist. In addition, it has been shown that seasonal shifts in diurnal cycles can be crucial.

The group identified an important need for better reporting of husbandry and procedures in published papers to allow evaluation and replication of the studies. It is hoped that online publishing will help resolve this problem, but participants recognize that a strong demand for complete disclosure of husbandry, including light management, is needed.

Suggested Citation:"Session 4: Environmental Control for Animal Housing." National Research Council. 2004. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington, DC: The National Academies Press. doi: 10.17226/11138.
×

TRANSITIONS

Our knowledge of the impact of transitions is weak, but we have reasonable scientific basis from field studies to consider that they may affect research outcomes and perhaps animal wellness. Rapid transitions will invoke alarm behaviors in several species, and the metabolic impacts of these transitions are poorly understood. Although considerable effort has been invested in managing diurnal cycles in some species and facilities, much less effort has gone into managing transitions. One possible challenge has been the wide spread use of fluorescent lighting, which requires relatively expensive electronics to dim. Those devices have also recently been shown to produce ultrasound at levels that could be problematic. The consensus of participants is that expense was the main driving force in the use of fluorescent lighting, and this in turn has resulted in limited options in light management.

WAVELENGTH/FREQUENCY

Dr. Blom posed the possibility that rodents could use red light during their active phase, which would also constitute a good approach for balancing the need for humans to see during the active phase. In this context, participants indicated the existence of gaps in the following areas:

  • The effect of red light;

  • Whether blue light is more appropriate for nocturnal periods;

  • The need to identify the ultraviolet (UV) requirements of various species (already known for some reptiles, birds, and insects, but largely extrapolated across mammals); and

  • Whether animals need exposure to a spectrum of full daylight.

FLICKERING

The issue of flickering was discussed because of challenges identified in Europe. Because 50 Hz is used as the typical cycle for power in Europe, fluorescent bulbs flicker at 50 Hz, rather than at 60 Hz, the cycle commonly used in the United States. The critical fusion frequency for an individual or species is the frequency at which a cycling light would be perceived as a continuous light source. The higher the critical fusion frequency of a species, the more likely they would be to perceive a fluorescent light as flickering on and off rather than providing steady light. This problem also occurs in humans and is the basis of considerable investigation relative to impacts on health and well-being. For cats, the critical fusion frequency is known to be slightly >50 Hz. For birds, the problem

Suggested Citation:"Session 4: Environmental Control for Animal Housing." National Research Council. 2004. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington, DC: The National Academies Press. doi: 10.17226/11138.
×

may be more acute because birds have a fourth type of cone that is sensitive to UV light and is phasic (i.e., sensitive to flickering up to 110 Hz).

Some participants suggested that potential problems from flicker perception should be studied in laboratory species. Others identified additional problems from fluorescent lights including generation of ultrasound by ballasts.

GAPS IN THE KNOWLEDGE

Among the many knowledge gaps related to light and laboratory species, the following areas clearly require additional information:

  • Knowledge of species and strain variations in susceptibilities and needs;

  • Natural history studies with communication to laboratory animal scientists (e.g., metabolic shifts, behavioral endocrine shifts);

  • Photoperiodicity studies;

  • Light acuity sensitivity data;

  • Studies on the effects of maintaining rodents under dim light with periods of increased light intensity; and

  • Studies of the effects of cage materials (e.g., clear vs. tinted walls) at actual light levels experienced in the cage itself (secondary enclosures) as opposed to the room.

ENGINEERING STANDARDS

Some participants felt that it is possible to spend so much time and effort on a particular engineering standard that time working with animal enrichment is severely decreased. Participants identified prioritization of effort as an important issue.

Similarly, it was felt that engineering standards can create important problems if based on poor data. This problem occurs particularly when engineering standards are too tightly defined and result in retarding the generation of new knowledge. It is common for engineering standards to conflict with performance standards.

EFFECT OF CURRENT REGULATIONS ON THE WELFARE OF THE ANIMALS

“Shoulds” tend to evolve into “musts.” There is a strong need for the use of adaptive management in many laboratory animal maintenance situations. In the absence of knowledge, the freedom to experiment and

Suggested Citation:"Session 4: Environmental Control for Animal Housing." National Research Council. 2004. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington, DC: The National Academies Press. doi: 10.17226/11138.
×

explore options is required. Participants indicated that investigators should be encouraged to study the effects of husbandry on their research.

It is possible for IACUC chairs to prefer strong and narrow regulations with tight interpretations to facilitate their ability to exert control over investigators who are not in optimal compliance. That approach, of functioning as a policeman and an enforcer, is one alternative; however, the approach of working with investigators as part of a team to improve animal welfare and care seems to be more effective.

IDENTIFICATION OF SIGNIFICANT DIFFERENCES AND CONFLICT (IF ANY) IN GUIDELINES/STANDARDS

This issue was not addressed during the session in detail because of time constraints, but the general position of the participants was to embrace performance-based standards in preference to specific engineering standards. This position was based largely on the perceived need to address a wide range of species and strains that may have different needs. Also of concern was the need to balance the lighting needs of animals with those of staff who are attempting to maintain the colony or conduct research.

Suggested Citation:"Session 4: Environmental Control for Animal Housing." National Research Council. 2004. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington, DC: The National Academies Press. doi: 10.17226/11138.
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Breakout Session: Effects of Sound on Research Animals

Leader: Sherri L. Motzel

Rapporteur: Hilton J. Klein

Gaps in our knowledge exist regarding the effects of noise, vibration, and sound for research animals. In this session, Dr. Sherri Motzel, Director of Laboratory Animal Resources at Merck Research Laboratories, presented a scholarly review of the effects of noise, vibration, and sound. The review included definitions, the current regulations and standards for noise, reviews of several relevant studies for rodents and nonhuman primates, and opportunities for noise, sound, and vibration mitigation. Dr. Motzel provided several references and cited relevant studies demonstrating that noise, vibration, and sound can have deleterious effects on behavioral and physiological parameters (Motzel et al. 2001; Sales and Milligan 1992; Sales et al. 1998, 1999).

Sound, which is produced when vibrating objects cause changes in air pressure, varies in duration, frequency (Hz), and magnitude or intensity (decibels, sound pressure level). Laboratory animals vary greatly by species in their ability to detect sound compared with humans. For example, humans detect sound from 20 Hz to 20 kHz, whereas rodent species are much more diverse in their ability to detect sound. Examples of range of detection include the following:

Mouse

0.8–100 kHz

Rat

0.25-76 kHz

Nonhuman primate (rhesus)

0.13-45 kHz

Dog

0.04-46 kHz

Suggested Citation:"Session 4: Environmental Control for Animal Housing." National Research Council. 2004. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington, DC: The National Academies Press. doi: 10.17226/11138.
×

Thus, animals detect sound inaudible to humans.

The US Animal Welfare Act regulations do not address noise. However, the ILAR Guide for the Care and Use of Laboratory Animals (NRC 1996) includes the recommendation to assess the effects of noise on animals, and to consider noise controls in animal facility design and construction. The Agricultural Guide (APHIS 1998) reflects greater tolerance toward the effects of noise on farm/agricultural animals, based on the few permanent effects reported in the literature cited therein. The Agricultural Guide does, however, include the recommendation that noise control should be considered during facility design. In contrast, the Council of Europe is clearer about the stressful effects of noise on laboratory animals and provides more specific recommendations in noise mitigation and control as well as for facility layout, design, and construction. In summary, regulations and standards for all laboratory animals address noise in a very basic and fundamental manner, yet they do not address the noise issue extensively because of a paucity of data on noise effects in the peerreviewed literature.

Dr. Motzel reviewed sources and types of sound and their effects in animal laboratory settings. Recorded sound levels vary widely but are dependent on species (e.g., barking dogs—99 dB) and on work practices, work cycles, and equipment.

Ultrasonic sound has been recorded from 24 of 39 sources (e.g., video displays, furniture, vacuums, and cage washers) and in some cases exceeds 100 kHz and 122 dB in frequency and intensity. It has been demonstrated clearly that ultrasonic sound creates perturbations in physiological parameters (e.g., heart rate, blood pressure, electroencephalographic changes), behavioral parameters (seizing), and teratogenic effects on laboratory animals.

Sound effects also vary in their impact, depending on the animal species, strain, and age. Dr. Motzel cited clear-cut effects of sound on response to drug treatment, water intake, blood pressure, reproduction, glucose metabolism, and immune function. One study conducted at Merck Research Laboratories by Dr. Motzel and her colleagues demonstrated conclusively that infrasound (1-10 Hz) was responsible for weight loss in CD rats in the study. A malfunctioning air handler was responsible for the source of the subsonic noise, which caused the weight loss. This study and other reports in the literature indicate that much more emphasis should be placed on monitoring and controlling noise levels at multiple frequency and intensity ranges outside human hearing ranges in animal facilities because of the potential for adverse effects on study data and outcomes. Preventive maintenance and facility testing, facility design, and work practices should also be reassessed in the laboratory animal facility in an effort to mitigate adverse noise effects. It was suggested that

Suggested Citation:"Session 4: Environmental Control for Animal Housing." National Research Council. 2004. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington, DC: The National Academies Press. doi: 10.17226/11138.
×

these strategies are effective for control and mitigation. Sound neutralizers and sound breaks were briefly mentioned as control devices for excessive noise problems.

In summary, the group agreed with Dr. Motzel’s assessments that in the context of behavioral and physiological effects, some laboratory animals are more sensitive to noise than humans. These effects are observed across a range of frequency, intensity, and duration that is much broader than in humans. Participants believed that for this reason, the current standards for the human environment may be of limited relevancy and not adequate to protect the integrity of research experiments. Additional in-depth review of the literature combined with relevant research studies to address noise effects in laboratory animals is clearly indicated. Participants agreed that current regulations and guidelines should be revised and updated accordingly.

SELECTED REFERENCES

APHIS [Animal Plant Health Inspection Service]. 1998. Regulation of agricultural animals (policy 26). In: Animal Care Resource Guide. Washington, DC: US Department of Agriculture.


Motzel, S.L., Morrisey, R.E., Conboy, T.A., and others. 1996. Weight loss in rats associated with exposure to infrasound. Contemp Topics 35:69.


NRC [National Research Council]. 1996. Guide for the Care and Use of Laboratory Animals. 7th ed. Washington, DC: National Academy Press.


Sales, G.D., and S.R. Milligan. 1992. Ultrasound and laboratory animals. Anim Technol 43:89-98.

Sales, G.D., Milligan, S.R., Khirnykh, K. 1999. Sources of sound in the laboratory animal environment: A survey of the sounds produced by procedures and equipment. Anim Welfare 8:97-115.

Sales, G.D., Wilson, K.J., Spencer, K.E.V., Milligan, S.R. 1998. Environmental ultrasound in laboratories and animal houses: A possible cause for concern in the welfare and use of laboratory animals. Lab Anim 22:369-375.

Suggested Citation:"Session 4: Environmental Control for Animal Housing." National Research Council. 2004. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington, DC: The National Academies Press. doi: 10.17226/11138.
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Breakout Session: Environmental Control for Animal Housing—Impact on Metabolism and Immunology

Leaders: Jann Hau and Randall J. Nelson

Rapporteur: Stephen W. Barthold

The introductory discussion focused on the impact of new guidelines on immune response and metabolism. Significant changes that may influence these responses include social grouping, environmental enrichment, and enclosure size.

Questions:

  1. Is there consistent scientific evidence for an impact of social environment (or environmental enrichment) on the immune system and metabolism?

    If so, is the evidence species specific?

  2. Is there a need for additional research on the impact of social environment or environmental enrichment on immune system and metabolism?

    If yes, in which areas?

  3. Is it possible to produce guidelines (or “best practices”) for group sizes of different species (strains, sexes, age groups) that would be optimal (i.e., not cause added variation to immune system and metabolism parameters)?

    Does the answer to this question depend on the project or parameter studied?

  4. Will there be a need for single housing to control variation with respect to immune system and metabolism?

  5. To develop “best practices” how should the group categorize the species (e.g., rodents vs. primates; solitary vs. social)?

Suggested Citation:"Session 4: Environmental Control for Animal Housing." National Research Council. 2004. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington, DC: The National Academies Press. doi: 10.17226/11138.
×
  1. Is it necessary to code these “best practices,” or is a mixed model of voluntary AND regulatory practices most sensible?

  2. Is it necessary to distinguish clearly between “stock and use” situations (i.e., one type of housing for the “hotel” period and another type of housing for the “experiment” period)?

  3. Is it necessary to consider the case of breeding colonies?

Drs. Hau and Nelson presented the following specific situations involving primates that illustrate these issues:

  • Single-housed gorillas have elevated cortisol (Stoinsky and others 2002).

  • Single housing of rhesus causes long-term immunosuppression (Lilly and others 1999).

  • Single housing of African green monkeys induces immunosuppression (Suleman and others 1999).

  • Pair housing of marmosets reduces cortisol response to novelty (Smith and others 1998).

  • Social separation of cynomolgus monkeys exacerbates atherosclerosis (Watson and others 1998).

  • Transfer from natal group to peer group of juvenile rhesus affects cortisol and T cell subsets (Gust and others 1992).

  • Separation of juvenile rhesus from natal group induces immunosuppression (Gordon and others 1992).

  • Formation of unrelated rhesus females into groups induces immunosuppression (Gust and others 1991).

  • Social group stress induces endothelial dysfunction in cynomolgus monkeys (Strawn and others 1991).

Examples of situations involving rats include the following:

  • Isolation advances puberty; enrichment delays puberty (Swanson and van de Poll 1983).

  • Single housing impairs testosterone synthesis and produces Leydig cell atrophy (Nyska and others 1998); increased exercise induces weight loss (Boakes and Dwyer 1997).

  • Group-housed rats are less stressed than single-housed (Sharp and others 2002, 2003) but are more vulnerable to stress-induced ulcers (Pare and others 1985).

  • Individually reared rats have a less than adequate response to aggression (Von Frijtag and others 2002).

  • Single housing (accompanied by stress) does not reduce the immune response of the rat to an antigen (Baldwin and others 1995).

Suggested Citation:"Session 4: Environmental Control for Animal Housing." National Research Council. 2004. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington, DC: The National Academies Press. doi: 10.17226/11138.
×
  • Single-housed rats are characterized by:

    • Higher levels of cortisol and prolactin (Gambardella and others 1994);

    • Increased substance P in the spinal cord (Brodin and others 1994);

    • Reduction of hypertension in obese rats; and

    • Reduced tumor growth (Steplewski and others 1987).

Examples of situations involving laboratory rodents include the following:

  • Single housing does not change glucocorticoid concentrations (Benton and Brain 1981; Misslin and others 1982) and does not affect reaction to a stressor (immunosuppression; Bartolomucci and others 2003).

  • Single housing induces immunosuppression (Shanks and others 1994).

  • Crowding males potentiates corticosterone response to acute stress (Laviola and others 2002).

  • Single-housed rats and mice behave differently in behavioral tests (Karolewicz and Paul 2001; Palanza and others 2001).

  • Minimal stress with four mice per cage compared with two or eight per cage (Peng and others 1989).

  • Male aggression is greater in groups of eight than in groups of three to five. Decreasing floor space decreases aggression (Van Loo and others 2001).

Social housing influences have included the following:

  • Expression of heat shock proteins (Andrews and others 2000);

  • Corticotropin-releasing factor and GABA receptors (Matsumoto and others 1997);

  • Chemotherapeutic efficacy (Kerr and others 1997, 2001);

  • Tumor growth (Kerr and others 2001; Rowse and others 1995; Weinberg and Emerman 1989);

  • Streptozotocin-induced hyperglycemia (Mazelis and others 1987); and

  • Hematopoiesis (Williams and others 1986).

Experience from immunization has been documented. Group-housed males have:

  • Higher cortisol levels and are immunosuppressed compared with single housed and family housed;

Suggested Citation:"Session 4: Environmental Control for Animal Housing." National Research Council. 2004. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington, DC: The National Academies Press. doi: 10.17226/11138.
×
  • Primary response to an antigen is low but response to booster injection is normal (Abraham and others 1994);

  • No reports on difference in titer (e.g., development in rabbits housed in different social groups).

Examples of the effect of enrichment include the following:

  • Barren-housed pigs have impaired long-term memory and blunted circadian cortisol rhythm (de Jong and others 2000).

  • Environmental enrichment stimulates the hypothalamic-pituitary-adrenal axis and the immune system in mice (Marashi and others 2003).

  • Numerous examples of the positive effect of enrichment on brain function are in the literature (e.g., reviews by Larsson and others 2002; Mattson and others 2001; Risedal and others 2002; Schrijver and others 2002).

VARIANCE IN EXPERIMENTAL RESULTS

The contribution of enrichment to variance in experimental results appears to depend on respective parameters. Dr. Nelson discussed the issue of density of animals in a room, using species variation as an example. He discussed data that indicated high-density populations result in high steroid concentrations and decreased immune function in mice (e.g., Csermely and others 1995; Tsukamoto and others 1994), but increased immune function in prairie voles (Nelson and others 1996). Thus, he concluded that intuition cannot be used in establishing guidelines, which reinforces the concept that guidelines must be science based and species sensitive.

Dr. Nevalainen presented data regarding volatile compounds in bedding, and environmental enrichment with variable material. Some bedding materials contain chemicals known as pinenes, which are heat labile, but induce hepatic microsomal enzymes (Nevalainen and Vartainen 1996). He also emphasized the need to utilize consistent materials for enrichment that are inert to other environmental materials to which the animals are exposed.

DISCUSSION AND POINTS RAISED BY PARTICIPANTS

One participant raised the issue of diet as another environmental variable that is not well controlled. There is a trend to replace some ingredients with others, such as replacing fish protein with casein. It was also noted that there is a growing number of rodents with suppressed immune responses due to highly hygienic husbandry practices among commercial

Suggested Citation:"Session 4: Environmental Control for Animal Housing." National Research Council. 2004. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington, DC: The National Academies Press. doi: 10.17226/11138.
×

breeders. Dr. Hardy cited an instance in which BALB/cByJ mice have a 4- to 10-fold decrease in total immunoglobulin (Ig)G, decreased mass to organized lymphoid tissue, and resulting shifts in immune reactivity. In highly sensitive studies, there is an increased trend of using gnotobiotic mice that are significantly affected by this phenomenon of immune system hypoplasia. For this reason, it was felt that it is important to determine the standards for rodent microflora. Users have a high sensitivity to issues relating to “microbial drift” in breeder colonies, which in turn have a large impact on breeders. Some strains of mice, including many transgenic mice, are more sensitive than others to these effects. Other effects of this immune hypoplasia syndrome include plasmacytogenesis in BALB mice primed with pristane, in which the mice have decreased yield and primarily IgM, rather than IgG. Susceptibility to other infections such as Giardia is also seen.

Biological endpoints have changed drastically and are generally more sensitive. Thus, the impact of environmental variables becomes more obvious and poses challenges for high-throughput analyses. How long do animals need to acclimate before being placed in test environments? Most people use a range of 24 hours to 5 days, but there have been no new data for more than 20 years. The animals may never acclimatize, such as when they are singly housed after having been maintained in a group.

Many participants indicated that guidelines and regulations are not the answer. The Materials and Methods sections in scientific publications must provide documentation of the study design, including such variables. Unfortunately, journals encourage less, rather than more, detail, which reduces the reproducibility of science and increases unnecessary use of animals to obtain reproducible results in other laboratories. The underlying principle is that “variance varies with various variables,” and guidelines or regulations with straight and narrow standards or limits interfere with this concept.

When discussing the possibility of developing guidelines for optimal group sizes, participants indicated that consideration needs to be given to factors such as species, sex, and strain, which make such rigid guidelines impossible. The answer depends on the project, and science must guide science, not rigid regulations. The current Guide (NRC 1996) dictates the number of mice per unit area of cage, and these guidelines, which are not based on science, are still often used as rigid standards. Considerable discussion revolved around the fact that the Guide is a guide, and that it is being misused by regulators. More details in any new iterations of the Guide will likely create more rules, without real benefit to animals or science. Dr. White’s presentation accurately depicted the reality. The Guide has only three musts in the entire book. IACUCs and regulatory agencies need better education regarding the purpose and limitations of the Guide.

Suggested Citation:"Session 4: Environmental Control for Animal Housing." National Research Council. 2004. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington, DC: The National Academies Press. doi: 10.17226/11138.
×

The Canadians seem to be doing the best, with a highly flexible and adaptive system of guidelines and oversight.

Finally, discussion of enriched versus nonenriched environments continued. Moving animals from unenriched production environments to different enriched environments for holding, then nonenriched environments for experimentation, creates enormous variation in response. Thus, it was felt that consideration must be given to the impact of new guidelines that may be well intentioned but not based on science and their impact on science.

REFERENCES

Abraham, L., O’Brien, D., Poulsen, O.M., Hau, J. 1994. The effect of social environment on the production of specific immunoglobulins against an immunogen (human IgG) in mice. In: Bunyan, J., ed. Welfare and Science. London: Royal Society of Medicine Press. p. 165-170.

Andrews, H.N., Kerr, L.R., Strange, K.S., Emerman, J.T., Weinberg, J. 2000. Effect of social housing condition on heat shock protein (HSP) expression in the Shionogi mouse mammary carcinoma (SC115). Breast Cancer Res Treat 59:199-209.


Baldwin, D.R., Wilcox, Z.C., Baylosis, R.C. 1995. Impact of differential housing on humoral immunity following exposure to an acute stressor in rats. Physiol Behav 57:649-653.

Bartolomucci, A., Sacerdote, P., Panerai, A.E., Peterzani, T., Palanza, P., Parmigiani S. 2003. Chronic psychosocial stress-induced down-regulation of immunity depends upon individual factors. J Neuroimmunol 141:58-64.

Benton, D., and Brain, P.F. 1981. Behavioral and adrenocortical reactivity in female mice following individual or group housing. Dev Psychobiol 14:101-107.

Boakes, R.A., and Dwyer, D.M. 1997. Weight loss in rats produced by running: effects of prior experience and individual housing. Q J Exp Psychol [B] 50:129-148.

Brodin, E., Rosen, A., Schott, E., Brodin, K. 1994. Effects of sequential removal of rats from a group cage, and of individual housing of rats, on substance P, cholecystokinin and somatostatin levels in the periaqueductal grey and limbic regions. Neuropeptides 26:253-260.


Csermely, P., Penzes, I., Toth, S. 1995. Chronic overcrowding decreases cytoplasmic free calcium levels in T lymphocytes of aged CBA/CA mice. Experientia 51:976-979.


de Jong, I.C., Prelle, I.T., van de Burgwal, J.A., Lambooij, E., Korte, S.M., Blokhuis, H.J., Koolhaas, J.M. 2000. Effects of environmental enrichment on behavioral responses to novelty, learning, and memory, and the circadian rhythm in cortisol in growing pigs. Physiol Behav 68:571-578.


Gambardella, P., Greco, A.M., Sticchi, R., Bellotti, R., Di Renzo, G. 1994. Individual housing modulates daily rhythms of hypothalamic catecholaminergic system and circulating hormones in adult male rats. Chronobiologia Int 11:213-221.

Gordon, T.P., Gust, D.A., Wilson, M.E., Ahmed-Ansari, A., Brodie, A.R., McClure, H.M. 1992. Social separation and reunion affects immune system in juvenile rhesus monkeys. Physiol Behav 51:467-472.

Gust, D.A., Gordon, T.P., Wilson, M.E., Brodie, A.R., Ahmed-Ansari, A., McClure, H.M. 1992. Removal from natal social group to peer housing affects cortisol levels and absolute numbers of T cell subsets in juvenile rhesus monkeys. Brain Behav Immun 6:189-199.

Suggested Citation:"Session 4: Environmental Control for Animal Housing." National Research Council. 2004. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington, DC: The National Academies Press. doi: 10.17226/11138.
×

Karolewicz, B., and Paul, I.A. 2001. Group housing of mice increases immobility and anti-depressant sensitivity in the forced swim and tail suspension tests. Eur J Pharmacol 415:197-201.

Kerr, L.R., Grimm, M.S., Silva, W.A., Weinberg, J., Emerman, J.T. 1997. Effects of social housing condition on the response of the Shionogi mouse mammary carcinoma (SC115) to chemotherapy. Cancer Res 57:1124-1128.

Kerr, L.R., Hundal, R., Silva, W.A., Emerman, J.T., Weinberg, J. 2001. Effects of social housing condition on chemotherapeutic efficacy in a Shionogi carcinoma (SC115) mouse tumor model: influences of temporal factors, tumor size, and tumor growth rate. Psychosomat Med 63:973-984.


Larsson, F., Winblad, B., Mohammed, A.H. 2002. Psychological stress and environmental adaptation in enriched vs. impoverished housed rats. Pharmacol Biochem Behav 73:193-207.

Laviola, G., Adriani, W., Morley-Fletcher, S., Terranova, M.L. 2002. Peculiar response of adolescent mice to acute and chronic stress and to amphetamine: evidence of sex differences. Behav Brain Res 130:117-125.

Lilly, A.A., Mehlman P.T., Higley, J.D. 1999. Trait-like immunological and hematological measures in female rhesus across varied environmental conditions. Am J Primatol 56:73-87.


Marashi, V., Barnekow, A., Ossendorf, E., Sachser, N. 2003. Effects of different forms of environmental enrichment on behavioral, endocrinological, and immunological parameters in male mice. Horm Behav 43:281-292.

Matsumoto, K., Ojima, K., Watanabe, H. 1997. Central corticotropin-releasing factor and benzodiazepine receptor systems are involved in the social isolation stress-induced decrease in ethanol sleep in mice. Brain Res 753:318-321.

Mattson, M.P., Duan, W., Lee, J., Guo, Z. 2001. Suppression of brain aging and neurodegenerative disorders by dietary restriction and environmental enrichment: molecular mechanisms. Mech Ageing Dev 122:757-778.

Mazelis, A.G., Albert, D., Crisa, C., Fiore, H., Parasaram, D., Franklin, B., Ginsberg-Fellner, F., McEvoy, R.C. 1987. Relationship of stressful housing conditions to the onset of diabetes mellitus induced by multiple, sub-diabetogenic doses of streptozotocin in mice. Diabetes Res 6:195-200.

Misslin, R., Herzog, F., Koch, B., Ropartz, P. 1982. Effects of isolation, handling and novelty on the pituitary—adrenal response in the mouse. Psychoneuroendocrinology 7:217-221.


Nelson, R.J., Fine, J.M., Moffatt, C.A., Demas, G.E. 1996. Photoperiod and population density interact to affect reproductive, adrenal, and immune function in male prairie voles (Microtus ochrogaster). Am J Physiol 270:R571-R577.

Nevalainen, T., and Vartainen, T. 1996. Volatile organics compounds in commonly used beddings before and after autoclaving. Scand J Lab Anim Sci 23:101-104.

NRC [National Research Council]. 1996. Guide for the Care and Use of Laboratory Animals. 7th ed. Washington, DC: National Academy Press.


Palanza, P., Parmigiani, S., vom Saal, F.S. 2001. Effects of prenatal exposure to low doses of diethylstilbestrol, o,p’DDT, and methoxychlor on postnatal growth and neurobehavioral development in male and female mice. Horm Behav 40:252-265.

Pare, W.P., Vincent, G.P., Natelson, B.H. 1985. Daily feeding schedule and housing on incidence of activity-stress ulcer. Physiol Behav 34:423-429.

Peng, X., Lang, C.M., Drozdowicz, C.K., Ohlsson-Wilhelm, B.M. 1989. Effect of cage population density on plasma corticosterone and peripheral lymphocyte populations of laboratory mice. Lab Anim 23:302-306.

Suggested Citation:"Session 4: Environmental Control for Animal Housing." National Research Council. 2004. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington, DC: The National Academies Press. doi: 10.17226/11138.
×

Risedal, A., Mattsson, B., Dahlqvist, P., Nordborg, C., Olsson, T., Johansson, B.B. 2002. Environmental influences on functional outcome after a cortical infarct in the rat. Brain Res Bull 58:315-321.

Rowse, G.J., Weinberg, J., Emerman, J.T. 1995. Role of natural killer cells in psychosocial stressor-induced changes in mouse mammary tumor growth. Cancer Res 55:617-622.


Schrijver, N.C., Bahr, N.I., Weiss, I.C., Wurbel, H. 2002. Dissociable effects of isolation rearing and environmental enrichment on exploration, spatial learning and HPA activity in adult rats. Pharmacol Biochem Behav 73:209-224.

Shanks, N., Renton, C., Zalcman, S., Anisman, H.1994. Influence of change from grouped to individual housing on a T-cell-dependent immune response in mice: antagonism by diazepam. Pharmacol Biochem Behav 47:497-502.

Sharp, J.L., Zammit, T.G., Azar, T.A., Lawson, D.M. 2002. Stress-like responses to common procedures in male rats housed alone or with other rats. Contemp Topics Lab Anim Sci 41:8-14.

Sharp, J., Zammit, T., Azar, T., Lawson, D. 2003. Stress-like responses to common procedures in individually and group-housed female rats. Contemp Topics Lab Anim Sci 42:9-18.

Smith, T.E., McGreer-Whitworth, B., French, J.A. 1998. Close proximity of the heterosexual partner reduces the physiological and behavioral consequences of novel-cage housing in black tufted-ear marmosets (Callithrix kuhli). Horm Behav 34:211-222.

Steplewski, Z., Goldman, P.R., Vogel, W.H. 1987. Effect of housing stress on the formation and development of tumors in rats. Cancer Lett 34:257-261.

Stoinski, T.S., Czekala, N., Lukas, K.E., Maple, T.L. 2002. Urinary androgen and corticoid levels in captive, male Western lowland gorillas (Gorilla g. gorilla): Age- and social group-related differences. Am J Primatol 56:73-87.

Strawn, W.B., Bondjers, G., Kaplan, J.R., Manuck, S.B., Schwenke, D.C., Hansson, G.K., Shively, C.A., Clarkson, T.B. 1991. Endothelial dysfunction in response to psychosocial stress in monkeys. Circ Res 68:1270-1279.

Suleman, M.D., Yole, D., Wango, E., Sapolsky, R., Kithome, K., Carlsson, H.E., Hau, J. 1999. Peripheral blood lymphocyte immunocompetence in wild African green monkeys (Cercopithecus aethiops) and the effects of capture and confinement. In Vivo 13:25-27

Swanson, H.H., and van de Poll, N.E. 1983. Effects of an isolated or enriched environment after handling on sexual maturation and behaviour in male and female rats. J Reprod Fertil 69:165-171.


Tsukamoto, K., Machida, K., Ina, Y., Kuriyama, T., Suzuki, K., Murayama, R., Saiki, C. 1994. Effects of crowding on immune functions in mice. Nippon Eiseigaku Zasshi 49:827-836.


Van Loo, P.L., Mol, J.A., Koolhaas, J.M., Van Zutphen, B.F., Baumans, V. 2001. Modulation of aggression in male mice: influence of group size and cage size. Physiol Behav 72:675-683.

Von Frijtag, J.C., Schot, M., van den Bos, R., Spruijt, B.M. 2002. Individual housing during the play period results in changed responses to and consequences of a psychosocial stress situation in rats. Dev Psychobiol 41:58-69.


Watson, S.L., Shively, C.A., Kaplan, J.R., Line, S.W. 1998. Effects of chronic social separation on cardiovascular disease risk factors in female cynomolgus monkeys. Atherosclerosis 137:259-266.

Weinberg, J., and Emerman, J.T. 1989. Effects of psychosocial stressors on mouse mammary tumor growth. Brain Behav Immun 3:234-246.

Williams, L.H., Udupa, K.B., Lipshitz, D.A. 1986. Evaluation of the effect of age on hematopoiesis in the C57BL/6 mouse. Exp Hematol 14:827-832.

Suggested Citation:"Session 4: Environmental Control for Animal Housing." National Research Council. 2004. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington, DC: The National Academies Press. doi: 10.17226/11138.
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Breakout Session: Environmental Control/ Engineering Issues

Leaders: Bernard Blazewicz and Dan Frazier

Rapporteur: Janet Gonder

Participants began by listing a series of issues for possible discussion. Topics included biosafety and biosecurity; ventilation rates and effectiveness of ventilation; ventilated caging systems; relative humidity control; sources of humidification; monitoring; need for filtration; and sources of contaminants. Several of these issues were discussed.

Discussion of the engineering issues related to biohazard research centered around biosafety level (BSL) 3 and BSL4 housing for agricultural animals and nonhuman primates. The impetus for this discussion is the new funding for facility construction for national and regional containment laboratories and other research programs. Current design and construction references include the Centers for Disease Control and Prevention (CDC/NIH) Biosafety in Microbiological and Biomedical Laboratories (BMBL), National Institutes of Health (NIH) Guidelines and Policies, and the US Department of Agriculture (USDA) document ARS 242.1M. Of the many design considerations for this type of facility, it has become apparent that interpretation of the requirements is changing as experience is gained with these facilities. Participants identified a need for tracking these changes and experiences. It was noted that some of this information is available through the American Biological Safety Association (ABSA). The need for consideration of system redundancy was discussed, along with the need for more information to enable institutions to perform adequate risk assessments to maintain safety. It was also pointed

Suggested Citation:"Session 4: Environmental Control for Animal Housing." National Research Council. 2004. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington, DC: The National Academies Press. doi: 10.17226/11138.
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out that there is a critical need for knowledgeable engineering staff in these facilities to monitor and maintain the systems.

Ventilation rates of 10 to 15 air changes per hour (ac/h) have been cited in the Guide for the Care and Use of Laboratory Animals (Guide) as a reasonable general guidance. However, it was agreed that in some circumstances less than 10 ac/h may be adequate, whereas in other cases, more than 15 ac/h are needed to address the cooling load. The general endorsement from the breakout group is that the design of facilities should begin with calculations of the cooling load posed by the intended use of a room, and that the efficiency of ventilation depends not only on the rate but also on the room airflow distribution and the microenvironment of the primary cage, among other factors. One particular gap identified by participants was how to determine cooling load in a room with ventilated caging systems, that is, how much of the load is removed from the room by the exhaust and how much heat is transferred to the room from the cage. Data are needed in this area.

This topic led to a discussion of ventilated caging systems. Approximately 12 systems are commercially available worldwide, and all are different in one or more respects. How can these systems be differentiated or evaluated for use under different use situations? Participants discussed a need for guidance on selection of ventilated caging systems based on criteria such as airflow balance to individual cages; airflow distribution within cages; ammonia levels; filtration expectations (e.g., control of particulates); temperature and humidity; containment (negative vs. positive pressure); noise; vibration; exhaust choices; and ergonomics. The group felt in general that standardized test methods for these and other parameters are needed.

Suggested Citation:"Session 4: Environmental Control for Animal Housing." National Research Council. 2004. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington, DC: The National Academies Press. doi: 10.17226/11138.
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Suggested Citation:"Session 4: Environmental Control for Animal Housing." National Research Council. 2004. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington, DC: The National Academies Press. doi: 10.17226/11138.
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The Development of Science-based Guidelines for Laboratory Animal Care is the summary of an international workshop held in Washington, DC, in November 2003 to bring together experts from around the world to discuss the available knowledge that can positively influence current and pending guidelines for laboratory animal care, identify gaps in that knowledge in order to encourage future research endeavors, and discuss the scientific evidence that can be used to assess the benefits and costs of various regulatory approaches affecting facilities, research, and animal welfare.

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