|
Items in cart [0] |
Questions? Call 888-624-8373 |
PAPERBACK + PDF PAPERBACK PDF BOOK PDF CHAPTERS Free Resources |
||||||||||||||||
|
||||||||||||||||
|
|
|||||||||||||||
| ||||||||||||||||||||||||||||||
|
||||||||||||||||||||||||||||||
| Copyright © 2009. National Academy of Sciences. All rights reserved. Terms of Use and Privacy Statement |
Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter.
Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 44
Husbandry
HOUSING
Caging
Caging is one of the primary components of a rodent's environment and
can influence the well-being of the animals it houses. Many types of caging
are available commercially. Those used to house rodents should have the
following features:
· They should accommodate the normal physiologic and behavioral
needs of the animals, including maintenance of body temperature, normal
movement and postural adjustments, urination and defecation, and, when
indicated, reproduction.
· They should facilitate the ability of the animal to remain clean and dry.
· They should allow adequate ventilation.
· They should allow the animals easy access to food and water and
permit easy refilling and cleaning of the devices that contain food and
water.
· They should provide a secure environment that does not allow ani-
mals to become entrapped between opposing surfaces or in ventilation openings.
· They should be free of sharp edges or projections that could cause
injury to the animals housed.
· They should be constructed so that the animals can be seen easily
without undue disturbance.
44
OCR for page 45
HUSBANDRY
45
· They should have smooth, nonporous surfaces that will withstand
regular sanitizing with hot water, detergents, and disinfectants.
· They should be constructed of materials that are not susceptible to
corrosion.
In selecting caging, one should pay close attention to the ease and
thoroughness with which a cage can be serviced and sanitized. In addition
to smooth, impervious surfaces that are free of sharp edges, cages should
have minimal corners, ledges, and overlapping surfaces, because these fea-
tures allow the accumulation of dirt, debris, and moisture. Cages should be
constructed of durable materials that can withstand rough handling without
~ . . . .
cupping or cracking.
Sanitizing procedures, such as autoclaving and exposure to ionizing
radiation, can alter the physical characteristics of caging materials over
time and can greatly shorten useful life. Rodent cages are most commonly
constructed of stainless steer 'or plastic (polyethylene, polypropylene, or
polycarbonate), each of which has advantages and disadvantages. Galva
~ _
nized metal and aluminum have also been used but are generally less ac-
ceptable because of their high potential for corrosion.
Most rodent cages have at least one wire or metal grid surface to fur-
nish ventilation and permit inspection of the animals in the'cage. Inspec-
tion of animals can be further facilitated by the use of transparent plastic
cages. Opaque plastic or metal cages might provide a more desirable envi-
ronment for some studies or breeding programs; however, adequate inspec-
tion of animals will usually require manipulation of each cage.
The bottoms of rodent cages can be either solid or wire. The floors of
solid-bottom cages usually are covered with bedding material that absorbs
urine and moisture from feces, thereby improving the quality of the cage
environment and allowing for easy removal of accumulated wastes. Solid-
bottom cages provide excellent support for rodents' feet, minimizing the
occurrence of pododermatitis and injuries. Wire-bottom cages are equipped
with a wire-mesh grid, the spaces in which are large enough to allow the
passage of feces. Generally, there are two to four wires per inch (2.5 cm) in
the grid. These cages are normally mounted on racks that suspend them
over waste-collection pans filled with absorbent material. This caging type
minimizes contact with feces and urine and is thought to improve cage
ventilation. However, careful consideration should be given to the size and
species of rodents to be housed in wire-bottom cages because if their feet
and legs can be entrapped in the wire ~rid, they can suffer severe trauma,
including broken bones. In addition, older, heavier rodents can develop
pododermatitis if the wires in the grid are too far apart or too small in
diameter to provide adequate support for the feet.
Specialized types of caging that serve specific functions are available
for rodents, including caging designed to collect excrete, monitor physi
_
OCR for page 46
46
RODENTS: LABORATORYANIMAL MANAGEMENT
ologic characteristics, test behavioral responses, control aspects of the physical
environment, and permit enhanced microbiologic control of the environ-
ment. Such caging can pose special cleaning and sanitation problems.
Various racking systems, both fixed and mobile, are available to hold
either solid-bottom or wire-bottom cages. Racks should be constructed of
durable, smooth-surfaced, nonporous materials that can be easily sanitized.
Mobile racks are most commonly used because they allow greater flexibil-
ity of room arrangement and are easier to clean than fixed racks. If fixed
racks are used, adequate steps should be taken to protect floors or walls
from damage caused by the weight of the racks and to provide for cleaning
under and between the racks. Some racks incorporate devices that auto
matically supply water directly to the cages they hold.
Housing Systems
Many types of housing systems with specialized caging and ventilation
equipment are available for rodents. Generally, the purpose of these hous-
ing systems is to minimize the spread of airborne microorganisms between
cages; but they often do not prevent transmission of nonairborne fomites.
The most frequently used of these systems is the filter-top cage, which has a
spun-bound or woven synthetic filter that covers the wire-mesh top of a
solid-bottom cage, thereby preventing the entry or escape of airborne par-
ticles that can act as fomites for unwanted microorganisms. The use of
filter tops restricts ventilation and can alter the microenvironment of the
rodents housed in the cages; therefore, to maintain a healthful environment,
it might be necessary to change the bedding and clean the cages more often
(Keller et al., 19891.
A cubicle (also called an Illinois cubicle or a cubical containment sys-
tem) is an enclosed area of a room capable of housing one or more racks of
cages. It is separated from the rest of the room by a door that usually opens
and closes vertically. The cubicle is supplied by air that moves under the
door from the room and is exhausted through the ceiling, or a separate air
supply is provided to the cubicle through an opening in a wall, the base, or
the ceiling. Cubicles have been used to reduce airborne cross contamina-
tion between groups of animals housed in conventional plastic or wire-
bottom cages (White et al., 19831. They provide better ventilation than
many housing methods, but they do not protect against fomite transmission
of microorganisms. Strict adherence to sanitation and other husbandry pro-
cedures is required if cubicles are to be used effectively.
In some housing systems, cages are individually ventilated with highly
filtered air. In some, exhaust air is also filtered or controlled in a way that
greatly minimizes the risk of contaminating animals in other cages and
personnel in the animal rooms. Such systems can overcome the disadvan
OCR for page 47
HUSBANDRY
47
sages of using nonventilated filter-topped cages while minimizing airborne
cross-contamination.
A housing system that is particularly useful for maintaining the micro-
biologic status of rodents has isolators made of rigid or flexible-film plastic
that are designed to enclose a group of rodent cages. Built-in gloves allow
the manipulation of animals and materials in the isolators. Isolators are
supplied with filtered air and have a filtered exhaust; at least one transfer
device is provided for moving sterilized or disinfected materials into the
isolator. To maintain the microbiologic status of an isolated group of ani-
mals, it is necessary to sterilize or otherwise disinfect all the interior sur-
faces of the isolators, and all materials introduced into the isolators should
be first sterilized or otherwise disinfected.
Space Recommendations
~. ~
It is generally assumed that there are critical measures of cage floor
area and cage height below which the physiology and behavior of labora-
tory rodents will be adversely affected, thereby affecting the well-being of
the animals and potentially influencing research outcomes. However, there
are very few objective data for determining what those critical measures are
or even whether such interactions exist. A number of studies designed to
evaluate the effects of space on population dynamics have been conducted
on wild and laboratory rodents housed in a laboratory environment (e.g.,
see Barnett, 1955; Christian and LeMunyan, 1958), but some of them used
caging systems different from those generally used in laboratory animal
facilities (e.g., see Davis, 1958; Joasoo and McKenzie, 1976; Thiessen,
1964~. Changes in behavior, reproductive performance, adrenal weights,
A. ~ -
glucocorticoid and catecholamine concentrations, immunologic function,
numbers of some kinds of white blood cells (usually lymphocytes), and
cage-use patterns have been assessed in those studies and suggested as
indicators of stress and compromised well-being (e.g., see Barrett and Stockham,
1963; Bell et al., 1971; Christian, 1960; Poole and Morgan, 1976; White et
al., 1989~. However, there has never been general agreement as to which
physiologic and behavioral characteristics are indicative of well-being in
rodents or what magnitude of change in them would be necessary to com-
promise the well-being of the animals.
With few objective data available, cage space recommendations have
been based on the results of surveys of existing conditions and professional
judgment and consensus. The Guide (NRC, 1996 et seq.) provides space
recommendations for rodents. Space recommendations have also been de-
veloped in other countries (CCAC, 1980; Council of Europe, 1990), but
they are not totally compatible with those in the Guide. It is important to
remember that space recommendations in the Guide serve only as a starting
OCR for page 48
48
RODENTS: LABORATORY ANIMAL MANAGEMENT
point for determining space required by rodents and might need adjustment
to fit the needs of the animals and the purposes for which they are housed.
Although comprehensive studies involving all the characteristics asso-
ciated with housing rodents are not available, sufficient information does
exist to suggest that individually housed rodents and group-housed rodents
have different space requirements. For the most part, laboratory rodents are
social animals and probably benefit from living in compatible groups (Brain
and Bention, 1979; NRC, 1978; White, 19901. Although more study is
needed, rodents maintained for long periods, as in lifetime studies, appear
to survive longer when housed in large, compatible social groups than when
housed in small groups or individually (Hughes and Nowak, 1973; Rao,
19901. Individual housing is sometimes necessitated by the nature of the
experimental protocol; in such instances, adequate space should be allotted
to allow the animals to make normal postural adjustments, which will de-
pend on the body size attained by the animals during the course of the
experiment. Under those circumstances, current space guidelines might not
be sufficient, especially if an animal's size exceeds the scope of the recom-
mendations.
Conversely, group-housed rodents would be expected to need less space
per animal than individually housed rodents because each animal can also
use the space of the other rodents with which it is housed. Studies have
found that compatible social groups of rodents do not use all the available
space recommended in current guidelines and probably do not require it for
well-being (White, 1990; White et al., 1989~. Rodents housed in compat-
ible groups share cage space by huddling together along walls and under
overhanging portions of the cage, such as feeders, as well as piling up on
top of each other during long rest periods. The center of the cage is used
infrequently.
Even if individually housed, rodents appear to prefer sheltered areas of
the cage, especially if those areas have decreased light and height. Provid-
ing such a confined space within a cage might be one way to enrich the
environment of rodents.
Sexually mature male rodents often fight when housed in groups for breeding
or other purposes, but this behavior has never been shown to be a function of
the amount of available floor space in the cage. Rather, the incidence of
fighting appears to be related more to combining males into groups when they
are sexually mature (especially if females are housed in the same room) or
have participated in mating programs. Increasing the cage space is not effec-
tive in preventing the development of such behavior or in eliminating it once it
has occurred. Only separation of the animals into individual cages or into
smaller, compatible groups is effective in eliminating fighting.
In determining adequate cage space, it is important to consider the
conditions of the experimental procedure and how long the animals will be
OCR for page 49
HUSBANDRY
49
housed. Animals that become debilitated during the course of an experi-
mental procedure might require increased cage space or an alteration in
caging to accommodate limitations in motion, recumbent positions, and the
need for alternative food and water sources. Older animals are less active
than younger animals and use less of the cage space or available activity
devices.
The Guide (NRC, 1996 et seq.) and other guidelines also recommend
cage heights. The recommendations do not appear to be related to the body
size of rodents nor to their normal locomotion patterns. Laboratory rodents
exhibit some vertical exploratory behavior when put into a new cage, and it
has been suggested that relatively high cages be provided to accommodate
this occasional behavior (Lawlor, 1990; Scharmann, 1991~. However, there
is no good evidence to suggest that rodents require tall enclosures. On the
contrary, as described previously, they tend to seek shelter under objects
lower than recommended in existing guidelines. Depending on the caging
type, existing height guidelines can be useful for ensuring that there is
adequate space for side-wall or cage-top feeders and adequate clearance for
sipper tubes or other watering devices.
In summary, the space required to maintain rodents, either individually
or in groups, depends on a number of factors, including age, weight, body
size, sexual maturity, experimental intervention, behavioral characteristics,
the duration of housing, group size, breeding activities, and availability of
enrichment devices or sheltering areas within the cage. The relationships
among those factors are complex, and there is not necessarily a direct corre-
lation between body weight or surface area of the animals and the absolute
floor area of the cage required or used by them. Guidelines should be used
with professional judgment based on assessment of the animals' well-being.
However, alterations that bring floor area or height of cages below recom-
mended levels should be adequately justified and approved by the IACUC.
ENVIRONMENT
Microenvironment
The microenvironment of a rodent is the physical environment that
immediately surrounds it and is usually considered to be bounded by the
primary enclosure or cage in which it resides. In contrast, the physical
conditions in the secondary enclosure or animal room make up the
macroenvironment. The components of the macroenvironment are often
easier to measure and characterize than those of the microenvironment. The
two environments are linked or coupled, but the character of each is often
quite different and depends on a variety of factors, such as the numbers and
species of rodents housed in the microenvironment, the design and con
OCR for page 50
50
RODENTS: LABORATORYANIMAL MANAGEMENT
struction of the cages, and the types of bedding materials used (Beech,
1975; Woods, 1975; Woods et al., 1975~.
The measurement of constituents of the microenvironment of rodents is
often difficult because of the relatively small volume of the primary enclo-
sure. Available data show that temperature, humidity, and concentrations
of gases and particulate matter such as carbon dioxide, ammonia, meth-
ane, sulfur dioxide, respirable particles, and bacteria are often higher in
the microenvironment than in the macroenvironment (Beech, 1980; Clough,
1976; Flynn, 1968; Gamble and Clough, 1976; Murakami, 1971; Serrano,
19711. Although there is little information on the relation between the
magnitude of exposure to some of those components and alterations in dis-
ease susceptibility or changes in metabolic or physiologic processes, the
available data clearly suggest that the characteristics of the microenviron-
ment can have a substantial impact on research results (Broderson et al.,
1976; Vessell et al., 1973, 1976~.
Temperature
Temperature and relative humidity are important components of the
environment of all animals because they directly affect an animal's ability
to regulate internal heat. They act synergistically to affect heat loss in
rodents, which lose heat by insensible means, rather than by perspiring.
Studies in the older literature, which were conducted without the benefit of
modern systems for controlling conditions precisely or modern instrumen-
tation, have established that extremes in temperature can cause harmful
effects (Lee, 1942; Mills, 1945; Mills and Schmidt, 1942; Ogle, 1934;
Sunstroem, 1927~. However, those studies were done on only a few labo-
ratory species.
Studies in the past generally focused on prolonged exposure of labora-
tory animals to temperatures above 85°F (29.4°C) or below 40°F (4.4°C),
which are required to achieve clinical effects (Baetjer, 1968; Mills, 1945;
Weihe, 1965~. When exposed to those extreme temperatures, rodents use
behavioral means (e.g., nest-building, curling up, huddling with others in
the cage, and adjusting activity level) to attempt to adapt. If the tempera-
ture change is brief or small, behavioral adaptation is sufficient; profound
or prolonged temperature changes generally require physiologic or struc-
tural adaptation as well. Physiologic adaptation includes alterations in
metabolic rate, growth rate, and food or water consumption; hibernation or
estivation; and the initiation of nonshivering thermogenesis. Structural ad-
aptation includes alterations in fat stores, density of the hair coat, and struc-
ture or perfusion of heat-radiating tissues and organs (e.g., tail, ears, scro-
tum, and soles of the feet). Initiation of such changes usually requires
exposure to an extreme temperature for at least 14 days.
OCR for page 51
HUSBANDRY
51
For routine housing of laboratory rodents, a consistent temperature range
should be provided. However, there is little scientific evidence from which
optimal temperature ranges for laboratory rodents can be determined. For
each species, there is a narrow range of environmental temperatures at which
oxygen consumption is minimal and virtually independent of change in
ambient temperature. The range in which little energy is expended to main-
tain body temperature is called the thermal neutral zone, and some have
suggested that it is a range of comfortable temperatures for rodents (Beech,
1985; Weihe, 1965, 1976a). However, other evidence suggests that animals
held within this temperature range do not necessarily achieve optimal growth
and reproductive performance, and the optimal temperature range might be
age-dependent (Blackmore, 1970; Weihe, 1965J. Moreover, measurements
of thermal neutral zones are generally made on resting animals and do not
take into account periods of increased activity or altered metabolic states,
such as pregnancy. Thermal neutrality does not necessarily equate with
comfort. In the absence of well-controlled studies that used objective mea-
sures for determining optimal ranges, recommended temperature ranges for
laboratory rodents have been independently developed by several groups on
the basis of professional judgment and experience (e.g., CCAC, 1980; Council
of Europe, 1990; NRC, 1996 et seq.~.
Humidity
Relative humidity varies considerably with husbandry and caging prac-
tices. In addition, there is usually a difference between the relative humid-
ity in the room and that in the animal cages. Many factors including cage
material and construction, use of filter tops, number of animals per cage,
frequency of bedding changes, and bedding type can affect the relative
humidity in the rodents' immediate environment.
Variations in relative humidity appear to be tolerated much better at
some temperatures than at others. Studies in humans and limited in vitro
work on survival of microorganisms have established a loose association
between humidity and susceptibility to disease (Baetjer, 1968; Dunklin and
Puck, 1948; Green, 1974; Webb et al., 1963), but there is no good evidence
to establish this link in animals. Low relative humidity has been reported to
be associated with the development of "ring tail" in rodents (Flynn, 1959;
Njaa et al., 1957; Stuhlman and Wagner, 1971~; however, this condition has
not been adequately studied and does not appear to be reproducible by
lowering relative humidity in controlled laboratory experiments.
Guidelines have been established for relative-humidity ranges based on
experience and professional judgment (CCAC, 1980; Council of Europe,
1990; NRC, 1996 et seq.~. There is no evidence to support limiting the
variation of relative humidity within these ranges; however, the combina
OCR for page 52
52
RODENTS: LABORATORYANIMAL MANAGEMENT
lion of high relative humidity and high environmental temperature can af-
fect the ability of rodents to dissipate heat by insensible means and should
be avoided.
Ventilation
Ventilation Rate
Ventilation refers to the process of using conditioned air to affect tem-
perature, humidity, and concentrations of gaseous and particulate contami-
nants in the environment. Ventilation is often characterized at the animal-
room level as air exchanges per hour. However, as for other environmental
conditions, there are no definitive data showing that the air-exchange range
in existing guidelines (i.e., 10-15 air changes/hour) provides optimal venti-
lation for laboratory rodents.
Existing guidelines have been criticized as being based mainly on keep-
ing odors below objectionable limits for humans (Beech, 1980; Runkle,
1964) and, in recent years, as being energy-intensive. An often-quoted
study by Munkelt (1938) appears to support the first contention: his mea-
sure of adequate ventilation was the ability to smell ammonia in the envi-
ronment. Besch (1980) suggested that ventilation should be based on air-
exchange rate per animal or animal cage because room air-exchange rates
do not consider such factors as population density, room configuration, and
cage placement within a room. Ultimately, however, the ventilation rate in
animal rooms is governed by the heat loads produced in the rooms, which
include not only heat produced by animals but also that produced by other
heat-radiating devices, such as lighting (Curd, 1976~.
Available evidence suggests that little additional control of the concen-
trations of gaseous and particulate contaminants is gained by using air-
exchange rates higher than those recommended in current guidelines (Barkley,
1978; Besch, 19801. The recommendation of providing a room air-ex-
change rate of 10-15 changes/hour is still useful; however, this ventilation
range might not be appropriate in some circumstances, especially if the
diffusion of air within the room is inappropriate for the type and placement
of cages. Other methods of providing equal or more effective ventilation,
including the use of individually ventilated cages or enclosures and the
adjustment of ventilation rate to accommodate unusual population densities,
are also acceptable.
Calculation of the amount of cooling required to control expected sen-
sible and latent heat loads generated by the species to be housed and the
largest expected population (ASHRAE, 1993) can be used to determine
minimal ventilation requirements. However, that calculation does not take
into account the generation of odors, particles, and gases, which might
necessitate greater ventilation.
OCR for page 53
HUSBANDRY
Air Quality
53
The quality of air used to ventilate animal rooms is another important
consideration. Ventilation systems for rodent rooms incorporate various
types of filtration of incoming air. Coarse filtration of the air supply is a
minimal requirement for proper operation of ventilating equipment. Most
facilities maintaining rodents of defined microbiologic status also use high-
efficiency particulate air (commonly called HEPA) filters to decrease the
risk of introducing rodent pathogens into the animal room through the fresh-
air supply (Dyment, 1976; Harstad et al., 1967~. The required filter effi-
ciency is a matter of professional judgment, and selection should be based
on the perceived likelihood of introducing contaminated air into the room.
Filtration of exhaust air from rodent rooms when air is not recycled is
usually deemed unnecessary unless the exhaust air is likely to contain haz-
ardous or infectious materials. Filters designed to remove chemicals from
air are sometimes incorporated into exhaust systems to remove animal odors.
Activated-chemical filters (e.g., those with activated charcoal) are often
used for this purpose; however, their efficiency in removing odoriferous
compounds, including ammonia, varies, and they require substantial mainte-
nance to remain effective.
The use of recycled air to ventilate animal rooms can save considerable
amounts of energy. However, many animal pathogens can be airborne or
travel on fomites, such as dust, so recycling of exhaust air into heating,
ventilating, and air-conditioning systems that serve multiple rooms presents
a risk of cross contamination. Exhaust air that is to be recycled should be
HEPA-filtered to remove particles. HEPA filters are available in various
efficiencies; the extent and efficiency of filtration should be proportional to
~ ~ 1 ~ ~ ~ ~ 1
the risk. toxic or odor-caus~ng gases produced oy aecompos~uon of animal
wastes can be removed by the ventilating system with chemical absorption
or scrubbing, but those methods might not be completely effective. Fre-
quent bedding changes and cage-cleaning, a reduction in number of animals
housed in a room, and a decrease in environmental temperature and humid-
itv within limits recommended in the Guide (NRC, 1996 et seq.) can
also assist in reducing the concentration of toxic or odor-caus~ng gases.
Treatment of recycled air to remove either particulate or gaseous contami-
nants is expensive and can be ineffective if filtration systems are improp-
erly or insufficiently maintained. Therefore, recycling systems require regular
monitoring for effective use.
An energy-recovery system that reclaims heat and thereby makes it en-
ergy-efficient to exhaust animal-room air totally to the outside is also accept-
able, but these systems often require much maintenance to be effective. The
recycling of air from nonanimal areas can be considered as an alternative to
the recycling of animal-room air, but this air might require filtering and treat-
ment to remove odors, toxic chemicals, and particles (White, 1982~.
OCR for page 54
54
Relative Air Pressures
R ODENTS: LAB ORA TOR Y ANIMAL MANA CEMENT
To minimize the potential for airborne cross-contamination between
adjacent rodent rooms or between rodent rooms and other areas where con-
taminants might be generated, it is important to consider controlling relative
air pressures. By adjusting the rates of air flow to and from individual
areas, one can produce a negative or positive pressure relative to adjoining
areas. When the intent is to contain contaminants (e.g., in areas used to
quarantine newly arrived animals, isolate animals infected or suspected of
being infected with rodent pathogens, house animals or materials inoculated
with biohazardous substances, or keep soiled equipment), air pressure in the
containment area should be lower than that in surrounding areas. When the
intent is to prevent the entry of contaminants, as in areas used to house
specific-pathogen-free rodents or keep clean equipment, air pressure in the
controlled area should be greater than that in surrounding areas. It is im-
portant to remember, however, that many factors influence disease trans-
mission between adjacent rooms; simply controlling air pressure is not suf-
ficient to prevent transmission.
Cage Ventilation
Ventilation can easily be measured in rodent-holding rooms; however,
conditions monitored in a room do not necessarily reflect conditions in the
cages in the room. The large sample volumes required by the commonly
used instruments that measure ventilation, as well as the size of the intruments
themselves, preclude accurate measurement in cages (Johnstone and Scholes,
1976~. The degree to which cages are ventilated by the room air supply is
affected by cage design; room air-diffuser type and location; number, size,
and type of animals in the cages; presence of filter tops; and location of the
cages. For example, cages without filter tops provide better air and heat
exchange than those with filter tops, in which ventilation is substantially
decreased (Keller et al., 19891. Rigidly maintaining room air quality and
ventilation will not necessarily provide the same environment for similar
groups of animals or even for similar cages in the same room. Individually
ventilated cages provide better ventilation for the animals and, possibly, a
more consistent environment (Lipman et al., 1992), but those systems are
generally expensive.
It has not been established whether rodents are uncomfortable when
exposed to air movements (drafts) or that exposure to drafts has biologic
consequences. However, movement of air in a room influences the ventila-
tion of an animal's primary enclosure and so is an important determinant of
microenvironment.
OCR for page 74
74
RODENTS: LABORATORYANIMAL MANAGEMENT
bowls, or automatic watering systems. Hamsters secrete highly concen-
trated urine that contains large quantities of mineral salts; their urine tends
to leave deposits on cage surfaces that are often difficult to remove and
might require the application of dilute acids.
Hamsters are often aggressive toward each other, and care should be
taken when they are housed in groups. Hamsters that fight must be sepa-
rated to prevent injury. Cannibalization can occur in group-housed animals
when an animal becomes sick or debilitated. It is important to separate
animals that are observed to be clinically abnormal.
Vitamin E is an important nutritional requirement of hamsters; vitamin
E deficiency has been associated with muscular dystrophy (West and Ma-
son, 1958J and fetal central nervous system hemorrhagic necrosis (Keeler
and Young, 19793. Most commercial rodent diets are supplemented with
vitamin E, but care is required to ensure the adequacy of vitamin E if
special-formula, purified, or semipurified diets are used (Balk and Slater,
1987~. The method of food presentation is important. If food is placed in
suspended feeders, hamsters will remove it from the feeder and pile it on
the floor. Location of the food pile is peculiar to individual hamsters and
will vary from one cage environment to the next. Moving food away from a
pile will cause the hamsters to retrieve it and move it back. Given that
behavioral pattern, feeding hamsters on the floor of the cage is considered
acceptable (9 CFR 3.291. Hamsters have cheek pouches in which they hold
and transport food; a full cheek pouch should not be mistaken for a pathologic
condition.
Hamsters have very loose skin, particularly over the shoulders. Care
should be taken when picking them up so that they do not turn around and
bite the handler. Hamsters can be tamed by regular, gentle handling. With-
out such taming, they can be aggressive toward the handler.
Many species of hamsters hibernate if conditions are right. Various
environmental influences seem important, including seasonality, photope-
riod, ambient temperature, availability of food, and isolation. To avoid
hibernation, temperatures should be maintained within ranges specified in
the Guide (NRC, 1996 et seq.~.
Hamsters, like guinea pigs, are susceptible to antibiotic associated tox-
icity and enterocolitis. Although successful use of antibiotics in hamsters
has been reported, the reports usually involve smaller than therapeutic dos-
ages of antibiotics or the use of particular antibiotic preparations that are
not excreted into the gastrointestinal tract (fakes et al., 1984; Small, 19871.
As a general rule, antibiotics should be avoided in hamsters.
Estrus in hamsters is similar to that in mice, lasting 4-5 days; however, the
gestation period is considerably shorter than that in mice an average of 16
days. Hamsters are commonly pair-mated; the female is taken to the male's
OCR for page 75
HUSBANDRY
75
cage for breeding on detection of a stringy vaginal discharge that occurs when
the female is in estrus. The female can be removed from the male's cage after
mating is observed; however, conception is sometimes improved by leaving
her with the male for 24 hours. Removing the female after that time mini-
mizes fighting and allows the male to breed with other females. For optimal
reproduction, the light cycle should be maintained at 14 hours of light and 10
hours of dark, which is slightly different from that for other rodents. Litter
size ranges from 4 to 16 pups; first litters tend to be smaller than subsequent
litters. Cannibalism of pups is common, especially in first litters. It is impor-
tant to furnish enough bedding or nesting material for the neonates to stay well
hidden and to provide the dam with enough food to allow her to be undis-
turbed from about 2-3 days before birth until about 7-10 days after birth (Balk
and Slater, 1987; Harkness and Wagner, 19891.
Gerbils
Gerbils (Meriones unguiculatus) do well in solid-bottom cages. Gerbils
tend to stand and sit upright and often exhibit a digging or scratching be-
havior in the corners of cages while in an upright posture. Therefore, cages
that are tall enough for this behavior are generally preferred.
Gerbils tend to form social relationships early in life, and groups estab-
lished at puberty tend to exhibit minimal fighting or other aggressive be-
havior; aggressive behavior is more common when individual animals are
put together later in life. New mates are not accepted easily. For those
reasons, it is prudent to select a paired-mating scheme for establishment of
colonies and not to regroup gerbils often.
Estrus in gerbils lasts 4-6 days; gestation in nonlactating females is
about 24-26 daYs. If females are bred in the postpartum period, implanta-
tion is delayed, and gestation can be as long as 48 days
A,
To avoid postpar
tum mating, the male can be removed from the cage, but he should be
returned to his mate within 2 weeks to decrease the possibility of fighting
(Harkness and Wagner, 19891. Average litter size is 3-7.
Gerbils are generally very tame and rarely bite unless mishandled. When
they are excited, they will jump and dart about to resist being caught.
Gerbils should not be suspended by holding their tails, because the skin
over the tail is relatively loose and can be pulled off easily.
Commercial rodent diets are usually acceptable for gerbils, provided
that they have a low fat content. Because of the gerbils' unique fat metabo-
lism, it is not uncommon for them to develop high blood cholesterol con-
centrations on diets containing fat at 4 percent or more. When fed a diet
high in fat, gerbils tend to store the fat and become obese. In females, the
fat accumulation can be associated with reproductive difficulty.
OCR for page 76
76
RODENTS: LABORATORYANIMAL MANAGEMENT
Chinchillas
Chinchillas (Chinchilla laniger) have been farmed for pelts since 13
animals were imported from South America to California in 1927. Most
domestic stock is believed to be descended from those animals (Anderson
and Jones, 1984~. Chinchillas can be housed in wire-mesh or solid-bottom
cages; the latter are preferred for breeding (Clark, 1984; Weir, 19761. They
are fastidious groomers and should be provided with a box containing a
mixture of silver sand and Fuller's earth for a short period daily to allow
dust bathing (Clark, 1984~. Chinchillas tolerate cold but are very sensitive
to heat; the suggested temperature is 20°C (68°F) (Weir, 19761. Commercial
chinchilla feed is available, but standard guinea pig rations can also be used
(Clark, 1984; Weir, 1976~. They might require a source of roughage, such
as hay (Weir, 1967~. Water and food should be made available ad libitum.
The system used most commonly for breeding chinchillas is to put one
male with several females in a large cage. However, females are larger than
males and are very aggressive toward both males and other females, and it
is necessary to provide refuges, such as nesting boxes, for animals that are
being attacked. An "Elizabethan collar" can be used to keep an aggressive
female from following an animal that she is attacking into its refuge. A
light:dark ratio of 14:10 hours is adequate (Weir, 1967~. The mean gesta-
tion period is 111 days, with a range of 105-118 days (Clark, 19841. Chin-
chilla litter size ranges from one to six, with a mean of two. The young are
born fully furred and with open eyes, and they begin eating solid food
within 1 week but are not completely weaned until they are 6-8 weeks old.
Females do not build nests.
REFERENCES
Algers, B., I. Ekesbo, and S. Stromberg. 1978. The impact of continuous noise on animal
health. Acta Vet. Scand. 67(Suppl.): 1 -26.
Alleva, J. J., M. V. Waleski, F. R. Alleva, and E. J. Umberger. 1968. Synchronizing, effect of
photoperiodicity on ovulation in hamsters. Endocrinology 82:1227-1235.
Anderson, K. V., F. P. Coyle, and W. K. O'Steen. 1972. Retinal degeneration produced by
low-intensity colored light. Exp. Neurol. 35:233-238.
Anderson, S., and J. K. Jones, Jr., eds. 1984. Orders and Families of Recent Mammals of the
World. New York: John Wiley and Sons. 686 pp.
Anthony, A., and J. E. Harclerode. 1959. Noise stress in laboratory rodents. II: Effects of
chronic noise exposures on sexual performance and reproductive function of guinea pigs.
J. Acoust. Soc. Am. 31:1437-1440.
ASHRAE (American Society Heating, Refrigeration, and A Engineers, Inc.). 1993. Chapter 9:
Environmental Control for Animals and Plants. In 1993 ASHRAE Handbook: Funda
mentals, I-P edition. Atlanta: ASHRAE
Baetjer, A. M. 1968. Role of environmental temperature and humidity in susceptibility to
disease. Arch. Environ. Health 16:565-570.
Balk, M. W., and G. M. Slater. 1987. Care and management. Pp. 61-67 in Laboratory Ham-
sters, G. L. Van Hoosier, Jr., and C. W. McPherson, eds. Orlando, Fla.: Academic Press.
OCR for page 77
HUSBANDRY
77
Bank, H. L., J. John, M. K. Schmehl, and R. J. Dratch. 1990. Bactercidal effectiveness of
modulated UV light. Appl. Environ. Microbiol. 56:3888-3889.
Barkley, W. E. 1978. Abilities and limitations of architectural and engineering features in
controlling biohazards in animal facilities. Pp. 158-163 in Laboratory Animal Housing.
Proceedings of a symposium organized by the ILAR Committee on Laboratory Animal
Housing and held September 22-23, 1976, in Hunt Valley, Maryland. Washington, D.C.:
National Academy of Sciences.
Barnett, S. A; 1955. Competition among wild rats. Nature 175:126-127.
Barrett, A. M., and M. A. Stockham. 1963. The effect of housing conditions and simple
experimental procedures upon the corticosterone level in the plasma of rats. J. Endocrinol.
26:97- 105.
Bell, R. W., C. E. Miller, J. M. Ordy, and C. Rolsten. 1971. Effects of population density and
living space upon neuroanatomy, neurochemistry, and behavior in the C57B1-10 mouse.
J. Comp. Physiol. Psychol. 75:258-263.
Bellhorn, R. W. 1980. Lighting in the animal environment. Lab. Anim. Sci. 30:440-450.
Besch, E. L. 1975. Animal cage from dry bulb and dewpoint temperature differentials.
ASHRAE Trans. 81 :549-558.
Besch, E. L. 1980. Environmental quality within animal facilities. Lab. Anim. Sci. 30:385-406.
Besch, E. L. 1985. Definition of laboratory animal environmental conditions. Pp. 297-315 in
Animal Stress, G. P. Moberg, ed. Bethesda, Md.: American Physiological Society.
Blackmore, D. 1970. Individual differences in critical temperatures among rats at various
ages. J. Appl. Physiol. 29:556-559.
Block, S. S., ed. 1991. Disinfection, Sterilization, and Preservation. 4th ed. Philadelphia:
Lea & Febiger. 1,162 pp.
Bock, G. R., and J. C. Saunders. 1977. A critical period for acoustic trauma in the hamster
and its relation to cochlear development. Science 197:396-398.
Brain, P., and D. Benton. 1979. The interpretation of physiological correlates of differential
housing in laboratory rats. Life Sci. 24:99-115.
Brainard, G. C. 1988. Illumination of animal quarters in microgravity habitats: Participation
of light irradiance and wavelength in the photo regulation of the neuroendocrine system.
Pp. 217-252 in Lighting Requirements in Microgravity Rodents and Nonhuman Pri-
mates, D. C. Holley, C. M. Winget, and H. A. Leon, eds. NASA Technical Memorandum
101077. Washington, D;C.: National Aeronautics and Space Administration.
Brainard, G. C. 1989. Illumination of laboratory animal quarters: Participation of light irradiance and
wavelength in the requlation of the neuroendocrine system. Pp. 69-74 in Science and Animals:
Addressing Contemporary Issues, H. N. Guttman, J. A. Mench, and R. C. Simmonds, eds.
Bethesda, Md.: Scientists Center for Animal Welfare. Available from SCAW, Golden Triangle
Building One, 7833 Walker Drive, Suite 340, Greenbelt, MD 20770.
Broderson, J. R.' J. Lindsey, and J. E. Crawford. 1976. The role of environmental ammonia in
respiratory mycoplasmosis of rats. Am. J. Pathol. 85:115-130.
Bucci, T. J. 1992. Dietary restriction: Why all the Interest? An overview. Lab Anim.
21 (6):29-34.
Burdick, C. K., J. H. Patterson, and B. T. Mozo, R.T. Camp, Jr.. 1978. Threshold shifts in
chinchillas exposed to octave bands of noise centered at 63 and 1000 Hz for three days
(a). J. Acoust. Soc. Am. 64:458-466.
CCAC (Canadian Council on Animal Care). 1980. Guide to the Care and Use of Experimental
Animals, Vol. 1. Ottawa: Canadian Council on Animal Care. 120 pp. Available from
CCAC, Constitution Square, Tower II, 315-350 Albert, Ottawa, Ontario, Canada K1R lBl.
Christian, J. J. 1960. Adrenocortical and gonadal responses of female mice to increased
population density. Proc. Soc. Exp. Biol. Med. 104:330-332.
Christian, J. J., and C. D. LeMunyan. 1958. Adverse effects of crowding on lactation and
reproduction of mice and two generations of their progeny. Endocrinology 63:517-529.
OCR for page 78
78
RODENTS: LABORATORYANIMAL MANAGEMENT
Clark, J. D. 1984. Biology and diseases of other rodents. Pp. 183-205 in Laboratory Animal
Medicine, J. G. Fox, B. J. Cohen, and F. M. Loew, eds. Orlando, Fla.: Academic Press.
Clarke, H. E., M. E. Coates, J. K. Eva, D. J. Ford, C. K. Milner, P. N. O'Donoghue, P. P.
Scott, and R. J. Ward. 1977. Dietary standards for laboratory animals: Report of the
Laboratory Animals Centre Diets Advisory Committee. Lab. Anim. (London) 11:1-28.
Clough, G. 1976. The immediate environment of the laboratory animal. Pp. 77-94 in Control
of the Animal House Environment, T. McSheehy, ed. Laboratory Animal Handbooks 7.
London: Laboratory Animals Ltd.
Coates, M. E., ed. 1987. ICLAS Guidelines on the Selection and Formulation of Diets for
Animals in Biomedical Research. London: Institute of Biology.
Coates, M. E., J. E. Ford, M. E. Gregory, and S. Y. Thompson. 1969. Effects of gamma-
irradiation on the vitamin content of diets for laboratory animals. Lab. Anim. (London)
3:39-49.
Council of Europe. 1990. European Convention for the Protection of Vertebrate Animals Used
for Experimental and Other Scientific Purposes. Strasbourg: Council of Europe. 53 pp.
Cunliffe-Beamer, T. L., L. C. Freeman, and D. D. Myers. 1981. Barbiturate sleeptime in mice
exposed to autoclaved or unautoclaved wood beddings. Lab. Anim. Sci. 31:672-675.
Curd, E. F. 1976. Heat losses and heat gains. Pp. 153-183 in Control of the Animal House
Environment, T. McSheehy, ed. Laboratory Animal Handbooks 7. London: Laboratory
Animals Ltd.
Davis, D. E. 1958. The role of density in aggressive behavior of house mice. Anim. Behav.
6:207-210.
Davis, T. A., C. W. Bales, and R. E. Beauchene. 1983. Differential effects of dietary caloric
and protein restriction in the aging rat. Exp. Gerontol. 18:427-435.
Dunklin, E. W., and T. T. Puck. 1948. The lethal effect of relative humidity on airborne
bacteria. J. Exp. Med. 87: 87- 101.
Dyment, J. 1976. Air filtration. Pp. 209-246 in Control of the Animal House Environment, T.
McSheehy, ed. Laboratory Animal Handbooks 7. London: Laboratory Animals Ltd.
Ediger, R. D. 1976. Care and management. Pp. 5-12 in The Biology of the Guinea Pig, J. E.
Wagner and P. J. Manning, eds. New York: Academic Press.
Engelbrecht, R. S., M. J. Weber, B. L. Salter, and C. A. Schmidt. 1980. Comparative
inactivation of viruses by chlorine. Appl. Environ. Microbiol. 40:249-256.
Ferguson, H. C. 1966. Effect of red cedar chip bedding on hexobarbital and phenobarbital
sleep time. J. Pharm. Sci. 55:1142-1143.
Fidler, I. J. 1977. Depression of macrophages in mice drinking hyperchlorinated water.
Nature 270:735-736.
Flynn, R. J. 1959. Studies on the aetiology of ringtail of rats. Proc. Anim. Care Panel 9:155-
160.
Flynn, R. J. 1968. A new cage cover as an aid to laboratory rodent disease control. Proc. Soc.
Exp. Biol. Med. 129:714-717.
Foster, H. L., C. L. Black, and E. S. Pfau. 1964. A pasteurization process for pelleted diets.
Lab. Anim. Care 14:373-381.
Fox, J. G., F. D. Aldrich, and G. W. Boylen, Jr. 1976. Lead in animal foods. J. Toxicol.
Environ. Health 1:461-467.
Gamble, M. R., and G. Clough. 1976. Ammonia build-up in animal boxes and its effect on rat
tracheal epithelium. Lab. Anim. (London) 10(2) :93 - 104.
Ganaway, J. R., A. M. Allen, and C. W. McPherson. 1965. Prevention of acute Bordetella
bronchiseptica pneumonia in a guinea pig colony. Lab. Anim. Care 15:156-162.
Geber, W. F. 1973. Inhibition of fetal osteogenesis by maternal noise stress. Fed. Proc.
32:2101-2104.
OCR for page 79
HUSBANDRY
79
Geber, W. F., T. A. Anderson, and B. Van Dyne. 1966. Physiologic responses of the albino
rat to chronic noise stress. Arch. Environ. Health 12:751-754.
Goodrick, C. L. 1978. Body weight increment and length of life: The effect of genetic
constitution and dietary proteins. J. Gerontol. 33: 184- 190.
Green, D. E., and P. K. Stumpf. 1946. The mode of action of chlorine. J. Amer. Water Works
Assoc. 38: 1301-1305.
Green, G. H. 1974. The effect of indoor relative humidity on absenteeism and colds in
schools. ASHRAE Trans. 80(2): 131-141.
Greenman, D. L., P. Bryant, R. L. Kodell, and W. Sheldon. 1982. Influence of cage shelf
level on retinal atrophy in mice. Lab. Anim. Sci. 32:353-356.
Guha, D., E. F. Williams, Y. Nimitkitpaisan, S. Bose, S. N. Dutta, and S. N. Pradhar. 1976.
Effects of sound stimulus on gastric secretion and plasma corticosterone level in rats.
Res. Commun. Chem. Pathol. Pharmacol. 13:273-281.
Hall, J. E., W. J. White, and C. M. Lang. 1980. Acidification of drinking water: Its effects on
seleccted biologic phenomena in male mice. Lab. Anim. Sci. 30:643-651.
Hann, V. 1965. Disinfection of drinking water with ozone. J. Am. Water Works Assoc.
48:1316.
1989. Biology and husbandry. Pp. 9-54 in The Biology
Harkness, J. E., and J. E. Wagner. 1
and Medicine of Rabbits and Rodents, 3rd ed. Philadelphia: Lea & Febiger.
Harstad, J. B., H. M. Decker? L. M. Buchanan, and M. E. Filler. 1967. Air filtration of
submicron virus aerosols. Am. J. Public Health Nations Health 57:2186-2193.
Helrich, K. ed. 1990. Official Methods of Analysis of the Association of Official Analytical
Chemists, 15th ed. Arlington, Va.: Association of Official Analytical Chemists (AOAC).
Available from AOAC, 2200 Wilson Boulevard, Suite 400, Arlington, VA 22109-3301.
Hermann, L. M., W. J. White, and C. M. Lang. 1982. Prolonged exposure to acid,
chlorine, or tetracycline in drinking water: effects on delayed-type hypersensitiv-
ity, hema~glutination titers, and reticuloendothelial clearance rates in mice. Lab.
Anim. Sci. 32:603-608.
Holick, M. F. 1989. Cutaneous synthesis of vitamin D: Can dietary vitamin D supplemetation
substitute for sunli:,ht? Pp. 63-68 in Science and Animals: Addressing Contemporary
Issues, H. N. Guttman, J. A. Mench, and R. C. Simmonds, eds. Bethesda, Md.: Scientists
Center for Animal Welfare. Available from SCAW, Golden Triangle Building One, 7833
Walker Drive, Suite 340, Greenbelt, MD 20770.
Hughes, P. C., and M. Nowak. 1973. The effect of the number of animals per cage on thc
growth of the rat. Lab. Anim. (London) 7:293-296.
Iwasaki, K., C. A. Gleiser, E. J. Masoro, C. A. McMahan, E.-J. Seo, and B. P. Yu. 1988.
Influence of the restriction of individual dietary components on longevity and age-related
disease of Fischer rats: the fat component and the mineral component. J. Gerontol.
43:B13-B21.
Joasoo, A., and J. M. McKenzie. 1976. Stress and the immune response in rats. Int. Arch.
Allergy Appl. Immunol. 50:659-663.
Johnstone. M. W., and P. F. Scholes. 1976. Measuring the environment. Pp. 113-128 in
Control of the Animal House Environment, T. McSheehy, ed. Laboratory Animal Iland
books 7. London: Laboratory Animals Ltd.
Kaufman, J. E. ed. 1987. IES Lighting Handbook. New York: Illuminating Engineering
Society of North America.
Keeler, R. F., and S. Young. 1979. Role of vitamin E in the etiology of spontaneous hemor-
rhagic necrosis of the central nervous system of fetal hamsters. Teratology 20:127-32.
Keenan, K. P.. P. F. Smith, and K. A. Soper. 1994. Effect of dietary (caloric) restriction on
aging, survival, pathology and toxicology. Pp. 609-628 in Pathobiology of the Aging
OCR for page 80
80
RODENTS: LABORATORY ANIMAL MANAGEMENT
Rat, vol. 2, W. Notter, D. L. Dungworth, and C. C. Capen' eds. International Life
Sciences Institute.
Keller, L. S., W. J. White, M. T. Snyder, and C. M. Lang. 1989. An evaluation of intra-cage
ventilation in three animal caging systems. Lab. Anim. Sci. 39:237-242.
Kelly, J. B., and B. Masterton. 1977. Auditory sensitivity of the albino rat. J. Comp. Physiol.
Psychol. 91:930-936.
Kimmel, C. A., R. O. Cook, and R. E. Staples. 1976. Teratogenic potential of noise in mice
and rats. Toxicol. Appl. Pharmacol. 36:239-245.
Knapka, J. J. 1983. Nutrition. Pp. 51-67 in The Mouse in Biomedical Research. Vol. III:
Normative Biology, Immunology, and Husbandry, H. L. Foster, J. D. Small, and J. G.
Fox, eds. New York: Academic Press.
Knapka, J. J. 1985. Formulation of diets. Pp. 45-59 in Methods for Nutritional Assessment of
Fats, J. Beare-Rogers, ed. Champaign, Ill.: American Oil Chemists Society. Available
from the American Oil Chemists Society, PO Box 3489, Champaign, IL 61826-3489.
Knapka, J. J., K. P. Smith, and F. J. Judge. 1974. Effect of open and closed formula rations
on the performance of three strains of laboratory mice. Lab. Anim. Sci. 24:480-487.
Kool, H. J., and J. Hrubec. 1986. The influence of ozone, chlorine and chlorine dioxide
treatment on mutagenic activity in drinking water. Ozone Sci. Eng. 8(3):217.
Kraak, W., and G. Hofmann. 1977. Detection of noise-induced physiological stress and
hearing loss in guinea pigs by means of an electrochleographic method. Arch.
Otorhinolaryngol. 215:301-310.
Kubo, C., B. C. Johnson, N. K. Day, and R. A. Good. 1984. Calorie source, caloric restric-
tion, immunity, and aging of (NZB/NZW) F1 mice. J. Nutr. 114:1884-1899.
Lai, Y.-L., R. O. Jacoby, and A. M. Jonas. 1978. Age-related and light-associated retinal
changes in Fischer rats. Invest. Ophthalmol. Vis. Sci. 17:634-638.
LaVail, M. M. 1976. Rod outer segment disk shedding in rat retina: relationship to cyclic
lighting. Science 194:1071-1074.
Lawlor, M. 1990. The size of rodent cages. Pp. 19-28 in Guidelines for the Well-being of
Rodents in Research, H. N. Guttman, ed. Proceedings from a conference organized by
the Scientists Center for Animal Welfare and held December 8, 1989, in Research Tri-
angle Park, North Carolina. Bethesda, Md.: Scientists Center for Animal Welfare.
Lee, R. C. 1942. Heat production of the rabbit at 28°C as affected by previous adaptation to
temperature between 10° and 31°C. J. Nutr. 23(1):83-90.
Ley, F. J., J. Bleby, M. E. Coates, and J. S. Patterson. 1969. Sterilization of laboratory animal
diets using gamma radiation. Lab. Anim. (London) 3:221-254.
Lipman, N. S., B. F. Corning, and M. A. Coiro. 1992. The effects of intracage ventilation on
microenvironmental conditions in filter-top cages. Lab. Anim. (Londor~) 26:206-210.
McEllhinev. R.. ed. 1985. Feed Manufacturin~ Technolo~v III. Arlin~ton. Va.: American
7 ~
~ - - =~ - O - 7
Feed Industry Association. 602 pp. Available from the American Feed Industry Associa-
tion, 1501 Wilson Boulevard, Arlington, VA 22209.
McKeown, T., and B. Macmahon. 1956. The influence of litter size and litter order on length
of gestation and early postnatal growth in guinea pigs. Endocrinology 13:195-200.
Meier, H., and M. C. Hoag. 1966. Blood coagulation. Pp. 373-376 in Biology of the
Laboratory Mouse, 2d ea., E. L. Green, ed. New York: McGraw-Hill Book Co.
Mills, C. A. 1945. Influence of environmental temperatures on warm-blooded animals. Ann.
N.Y. Acad Sci. 46(1):97-105.
Mills, C. A., and L. H. Schmidt. 1942. Environmental temperatures and resistance to infec-
tion. Am. J. Trop. Med. 22:655-660.
Moller, A. 1978. Review of animal experiments. J. Sound Vibr. 59:73-77.
Munkelt, H. F. 1938. Odor control in animal laboratories. Heat. Piping Air Cond. 10:289-
291.
OCR for page 81
HUSBANDRY
81
Murakami, H. 1971. Differences between internal and external environments of the mouse
cage. Lab. Anim. Sci. 21(5):680-684.
National Safety Council. 1979. Disposal of Potentially Contaminated Animal Wastes. Data
Sheet 1-167-79. Chicago: National Safety Council.
National Sanitation Foundation International. 1990. Standard 3: Commercial Spray-type
Dishwashing Machines. Ann Arbor, Mich.: National Sanitation Foundation Interna-
tional. Available from the National Sanitation Foundation International, 3475 Plymouth
Road, PO Box, 130140, Ann Arbor, MI 48113-0140 (telephone, 313-769-8010).
Navia, J. M. 1977. Preparation of diets used in dental research. Pp. 151-167 in Animal
Models in Dental Research. University, Ala.: University of Alabama Press.
Nayfield, K. C., and E. L. Besch. 1981. Comparative responses of rabbits and rats to elevated
noise. Lab. Anim. Sci. 31:386-390.
Nevins, R. G., and P. L. Miller. 1972. Analysis, evaluation and comparison of room air
distribution performance A summary. ASHRAE Trans. 28(2):235-242.
Newberne, P. M. 1975. Influence on pharmacological experiments of chemicals and other
factors in diets of laboratory animals. Fed. Proc. 34:209-218.
Newell, G. W. 1980. The quality, treatment, and monitoring of water for laboratory rodents.
Lab. Anim. Sci. 30(2, part II):377-384.
Njaa, L. R., F. Utne, and O. R. Braekkan. 1957. Effect of relative humidity on rat breeding
and ringtail. Nature 180:290-291.
NRC (National Research Council), Institute of Laboratory Animal Resources, Committee on
Care and Use of Laboratory Animals. 1978. Guide for the Care and Use of Laboratory
Animals. DHEW Pub. No. (NIH) 78-23. Washington, D.C.: U.S. Department of Health,
Education, and Welfare. 70 pp.
NRC (National Research Council), Institute of Laboratory Animal Resources, Committee to
Revise the Guide for the Care and Use of Laboratory Animals. 1996. Guide for the Care
and Use of Laboratory Animals, 7th edition. Washington, D.C.: National Academy Press.
NRC (National Research Council), Board on Agriculture, Committee on Animal Nutrition,
Subcommittee on Laboratory Animal Nutrition. 1995. Nutrient Requirements of Labora-
tory Animals, 4th revised ed. Nutrient Requirements of Domestic Animals Series. Wash-
ington, D.C.: National Academy Press.
Ogle, C. 1934. Climatic influence on the growth of the male albino mouse. Am. J. Physiol.
107:635-640.
O'Steen, W. K. 1970. Retinal and optic nerve serotonin and retinal degeneration as influ-
enced by photoperiod. Exp. Neurol. 27:194-205.
Pakes, S. P., Y.-S. Yu, and P. C. Meunier. 1984. Factors that complicate animal research. Pp.
649-665 in Laboratory Animal Medicine, J. G. Fox, B. J. Cohen. and F. M. Loew, eds.
Orlando, Fla.: Academic Press.
Peterson, E. A. 1980. Noise and laboratory animals. Lab. Anim. Sci. 30:2 Pt. II 422-439.
Peterson, E. A., J. S. Augenstein, D. C., Tanis, and D. G. Augenstein. 1981. Noise raises
blood pressure without impairing auditory sensitivity. Science 211:1450-1452.
Pleasants, J. R. 1984. Diets for germ-free animals. Part 2: The germ-free animal fed
chemically defined ultrafiltered diet. Pp. 91-109 in The Germ-Free Animal in Biomedi-
cal Research, M. E. Coates and B. E. Gustatsson, eds. London: Laboratory Animals Ltd.
Pleasants, J. R., M. H. Johnson, and B. S. Wostmann. 1986. Adequacy of chemically defined,
water-soluble diet for germ free BALB/c mice through successive generations and litters.
J. Nutr. 116: 1949- 1964.
Poole, T. B., and H. D. R. Morgan. 1976. Social and territorial behavior of laboratory mice
(Mus musculus L.) in small complex areas. Anim. Behav. 24:476-480.
Porter, G., and W. Lane-Petter. 1965. The provision of sterile bedding and nesting materials
with their effects on breeding mice. J. Anim. Tech. Assoc. 16:5-8.
OCR for page 82
82
R ODENTS: LAB ORA TOR Y. ANIMAL MANA CEMENT
Rao, G. N. 1990. Long-term toxicological studies using rodents. Pp. 47-52 in Guidelines for
the Well-being of Rodents in Research, H. N. Guttman, ed. Proceedings from a confer-
ence organized by the Scientists Center for Animal Welfare and held December 8, 1989,
in Research Triangle Park, North Carolina. Bethesda, Md.: Scientists Center for Animal
Welfare.
Rao, G. N., and J. J. Knapka. 1987. Contaminant and nutrient concentrations of natural
ingredient rat and mouse diet used in chemical toxicology studies. Fundam. Appl. Toxicol.
9:329-338.
Reiter, R. J. 1991. Pineal gland: Interface between the photoperiodic environment and the
endocrine system. Trends Endocrinol. Metab. 2: 13- 19.
Reme, C. E., A. Wirz-Justice, and M. Terman. 1991. The visual input stage of the mammalian
circadian pacemaking system. I. Is there a clock in the mammalian eye?. J. Biol.
Rhythms 6(1):5-29.
Runkle, R. S. 1964. Laboratory animal housing Part II-. J. Am. Inst. Arch. 41:77-80.
Scharmann, W. 1991. Improved housing of mice, rats and guinea pigs: A contribution to the
refinement of animal experiments. ATLA 19:108-114. ATLA (Alternatives to Labora-
tory Animals) is published by the Fund for Replacement of Animals in Medical Experi-
ments, Eastgate House, 34 Stoney Street, Nottingham NG1 1NB, England.
Serrano, L. J. 1971. Carbon dioxide and ammonia in mouse cages: Effect of cage covers,
population and activity. Lab. Anim. Sci. 21(1):75-85.
Small, J. D. 1987. Drugs used in hamsters with a review of antibiotic-associated colitis. Pp.
179-199 in Laboratory Hamsters, G. L. Van Hoosier, Jr. and C. W. McPherson, eds.
Orlando, Fla.: Academic Press.
Snyder, D. L. 1989. Dietary Restriction and Aging. Progress in Clinical and Biological
Research, vol 287. New York: Liss.
Society for Research on Biological Rhythms. 1993. Animals issues statement. J. Biol.
Rhythms.
Stotzer, V. H., I. Weisse, F. Knappen, and R. Seitz. 1970. Die Retina-Degeneration der Ratte.
Arzneim. Forsch. 20:811 -817.
Stuhlman, R. A., and J. E. Wagner. 1971. Ringtail in Mystromys albicaudatus: A case report.
Lab. Anim. Sci. 21:585-587.
Sundstroem, E. S. 1927. The physiological effects of tropical climate. Physiol. Rev. 7:320-362.
Terman. M., C. E. Reme, and A. Wirz-Justice. 1991. The visual input stage of the mammalian
circadian pacemaking system: II. The effect of light and drugs on retinal function. J.
Biol. Rhythms 6(1):31-48.
Thiessen, D. D. 1964. Population density, mouse genotype and endocrine function in behav-
ior. J. Comp. Physiol. Psychol. 57:412-416.
Thorington, L. 1985. Spectral, irradiance, and temporal aspects of natural and artificial lig,ht.
Ann. N.Y. Acad. Sci. 453:28-54.
Tobin, R. S. 1987. Testing and evaluating point-of-use treatment devices in Canada. J. Am.
Water Works Assoc. Oct., 42-45.
Tobin, R. S., D. K. Smith, and J. A. Lindsay. 1981. Effects of activated carbon and bacterio-
static filters on microbiological quality of drinking water. Appl. Environ. Microbiol.
41 :646-651.
Vesell, E. S. 1967. Induction of drug-metabolizing enzymes in liver microsomes of mice and
rats by softwood bedding. Science 157:1057-1058.
Vesell, E. S., C. M. Lang, W. J. White, G. T. Passananti, and S. L. Tripp. 1973. Hepatic drug
metabolism in rats: impairment in a dirty environment. Science 179:896-897.
Vesell, E. S., C. M. Lang, W. J. White, G. T. Passananti, R. N. Hill, T. L. Clemens, D. K. Liu,
and W. D. Johnson. 1976. Environmental and genetic factors affecting the response of
laboratory animals to drugs. Fed. Proc. 35:1125-1132.
OCR for page 83
HUSBANDRY
83
Wagner, J. E. 1976. Miscellaneous disease conditions of guinea pigs. Pp. 227-234 in The
Biology of the Guinea Pig, J. E. Wagner and P. J. Manning, eds. New York: Academic
Press.
Wardrip, C. L., J. E. Artwohl, and B. T. Bennett. 1994. A review of the role of temperature
versus time in an effective cage sanitation program. Contemp. Top. 33 (5):66-68.
Webb, S. J., R. Bather, and R. W. Hodges. 1963. The effect of relative humidity and inositol
on air-borne viruses. Can. J. Microbiol. 9:87-92.
Wegan, R. W. 1982 Alternative disinfection methods- a comparison of UV and ozone.
Industrial Water Engineering, March/April, 12-25.
Weihe, W. H. 1965. Temperature and humidity climatograms for rats and mice. Lab. Anim.
Care 15(1):18-28.
Weihe, W. H. 1976a. The effects on animals of changes in ambient temperature and humidity.
Pp. 41-50 in Control of the Animal House Environment, T. McSheehy, ed. Laboratory
Animal Handbooks 7. London: Laboratory Animals Ltd.
Weihe, W. H. 1976b. Influence of light on animals. Pp. 63-76 in Control of the Animal
House Environment, T. McSheehy, ed. Laboratory Animal Handbooks 7. London: Laboratory
Animals Ltd.
Weindruch, R., and R. L. Walford. 1988. The Retardation of Aging and Disease by Dietary
Restriction. Springfield, Ill.: Charles C Thomas.
Weir, B. J. 1967. The care and management of laboratory hystricomorph rodents. Lab. Anim.
(London) 1 :95- 104.
Weir, B. J. 1976. Laboratory hystricomorph rodents other than the guinea-pig and chinchilla.
Pp. 284-292 in The UFAW Handbook on the Care and Management of Laboratory Ani-
mals, 5th ed, Universities Federation for Animal Welfare, eds. Edinburgh: Churchill
Livingstone.
Weisse, I., H. Stotzer, and R. Seitz. 1974. Age- and light-dependent changes in the rat eye.
Virchows Arch. A 362:145-156.
West, W. T., and K. E. Mason. 1958. Histopathology of muscular dystrophy in the vitamin E
deficient hamster. Am. J. Anat. 102:323.
White, W. J. 1982. Energy savings in the animal facility: Opportunities and limitations. Lab
Anim. 2(2):28-35.
White, W. J. 1990. The effects of cage space and environmental factors. Pp. 29-44 in
Guidelines for the Well-being of Rodents in Research, H. N. Guttman, ed. Proceedings
from a conference organized by the Scientists Center for Animal Welfare and held De-
cember 8, 1989, in Research Triangle Park, North Carolina. Bethesda, Md.: Scientists
Center for Animal Welfare.
White, W. J., H. C. Hughes, S. B. Singh, and C. M. Lang. 1983. Evaluation of a cubical
containment system in preventing gaseous and particulate airborne cross-contamination.
Lab. Anim. Sci. 33:571-576.
White, W. J., M. W. Balk, and C. M. Lang. 1989. Use of cage space by guinea pigs. Lab.
Anim. (London) 23:208-214.
Williams, F. P., R. J. Christie, D. J. Johnson, and R. A. Whitney, Jr. 1968. A new autoclave
system ~r sterilizing vitamin-fortified commercial rodent diets with lower nutrient loss.
Lab. Anim. Care 18: 195-199.
Williams, T. P. 1989. Ambient lighting and integrity of the retina. Pp. 75-78 in Science and
Animals: Addressing Contemporary Issues, H. N. Guttman, J. A. Mench, and R. C.
Simmonds, eds. Bethesda, Md.: Scientists Center for Animal Welfare. Available from
SCAW, Golden Triangle Building One, 7833 Walker Drive, Suite 340, Greenbelt, MD
20770.
Williams, T. P., and B. N. Baker, eds. 1980. The Effects of Constant Light on Visual
Processes. New York: Plenum Press.
OCR for page 84
84
RODENTS: LABORATORYANIMAL MANAGEMENT
Woods, J. E. 1975. Influence of room air distribution on animal cage enviroments. ASHRAE
Trans. 81 :559-570.
Woods, J. E. 1978. Interactions between primary (cage) and secondary (room) enclosures.
Pp. 65-83 in Laboratory Animal Housing. Proceedings of a symposium organized by the
ILAR Committee on Laboratory Animal Housing and held September 22-23, 1976, in
Hunt Valley, Maryland. Washington, D.C.: National Academy of Sciences.
Woods, J. E., R. G. Nevins, and E. L. Besch. 1975. Analysis of thermal and ventilation
requirements for laboratory animal cage environments. ASHRAE Trans. 81:45-66.
Wurtman, R. J., M. J. Baum, and J. T. Potts, Jr., eds. 1985. The medical and biological effects
of light. Ann. N.Y. Acad. Sci. 453:1-408.
Yang, R. S., W. F. Mueller, H. K. Grace, L. Golberg, and F. Coulston. 1976. Hexachlorobenzene
contamination in laboratory monkey chow. J. Agric. Food Chem. 24:563-565.
Yu, B. P. 1990. Food restriction: Past and present status. Rev. Biol. Res. Aging 4:349-371.
Yu, B. P., E. J. Masoro, and C. A. McMahan. 1985. Nutritional influences on aging of
Fischer 344 rats: I. Physical, metabolic, and longevity characteristics. J. Gerontol.
40:657-670.
Zigman, S., and T. Vaughan. 1974. Near-ultraviolet light effects on the lenses and retinas of
mice. Invest. Ophthalm
Representative terms from entire chapter:
laboratory rodents
