Cage Space Requirements
Copyright 2003, University of Minnesota
Board of Regents.
The University of Minnesota is an equal
opportunity educator and employer.
The caging or housing system is an
important factor in the physical environment of
laboratory animals. It can influence the well-being of the
animals and/or act as an experimental variable. Federal
guidelines for use of vertebrate animals in research
contain specific provisions for basic husbandry. Proper
diet and a stress-free, sanitary environment are some of
the greatest tools in preventing the development or
transmission of disease. The following guidelines are
used by RAR in developing our husbandry procedures. They
are adapted from requirements in the Animal Welfare Act, the Guide for the Care and
Use of Laboratory Animals, and from the collective
experience of RAR animal care providers. If University
investigators have received permission from the IACUC to
provide their own animal care these guidelines apply.
- All animal housing areas must be checked daily, including
weekends and holidays, no exceptions.
- This check
animals for health problems
food and water levels
for proper cage/enclosure conditions
of the needs for each of these items is
should be evaluated based on the potential for
adverse effects on the animals and remedied as
soon as possible.
of daily checks should be provided in the form of
a room Standard Operating Procedure (SOP), a log
or a check list.
health status must be monitored at least
once daily, including weekends and
holidays, no exceptions.
with specific health problems, animals
recovering from anesthesia, or animals on
studies that have the potential for
rapidly changing the animals
condition (e.g. infectious disease, tumor
induction, toxicity) may require more
Signs of Disease
signs of disease can be extremely
variable depending on the species of
animal and the condition being monitored.
in behavior, food or water consumption,
fecal or urine output, reduction in
grooming behavior, aggression, muscular
rigidity, hair coat, reaction to handling can be
nonspecific signs of distress or disease.
specific signs or objective measurements
of organ dysfunction should be monitored
if indicated by the animals
condition or the expected impact of the
information is available from RAR.
animals used for research, testing or
teaching at the University of Minnesota
must have an attending veterinarian
available. If animals are not housed in RAR associated facilities, the veterinary oversight should be indicated on the protocol.
care must be available on holidays and
weekends as well as during work hours.
Animal Resources can provide veterinary
consultation on request.
animal room must be kept clean, quiet,
and uncluttered. The use of procedure
rooms is encouraged whenever possible.
Research procedures which are permitted
within the room include injections, blood
collection, examinations and other
noninvasive techniques. Procedures which
are not permitted in the animal room, except in a vented biosafety cabinet,
include surgery, euthanasia and necropsy. Exceptions may be made in special circumstances such as quarantine..
levels should be adequate for the animal
to perform normal behaviors and for the
animal care giver to perform their
duties. Diffuse lighting in the range of
130-325 lux are normal for mammal husbandry.
light cycle should be appropriate for the
biology of the animal, if consistent with
experimental goals. A diurnal 12 hour
light cycle for most species and 14 hour light /10 hour dark for breeding colonies of rats and mice are standard. Reversal of the
cycle or alteration of the cycle may be
desirable depending on the experiment.
- Ventilation for rooms housing mammalian species must be adequate to provide
oxygen and remove chemical, biological,
and heat waste. The standard rate is
10-15 air changes per hour. Lower levels
may be acceptable if animal density in
the room is low. Fresh air supply and 100% exhaust air to the outside is the standard ventilation requirement.
ventilation should normally be adjusted
to maintain room pressure relative to the corridor as positive for SPF animals or negative if the
room is serving as an isolation room.
ducts and filters should be cleaned at
in rooms should be maintained in a range
suitable for the species of animal and
the animals should be protected from
range of 68° F to 74° F is standard for
- Amphibians, reptiled, fish, birds and animals adapted to outdoor environments
may have different needs.
ranges for many animals are specified in
the Animal Welfare Act and the Guide for the Care and Use of Laboratory Animals.
may detect different sound frequencies
than do human beings. Therefore, noise in
animal rooms should be minimized whenever
- Playing music in animal
rooms is not allowed, although it may be permitted under
some circumstances to provide enrichment
or "white noise".
from mechanical equipment in adjacent
areas should be avoided.
species may experience reproductive
problems when exposed to excessive noise.
surfaces should be constructed of
material that is easily sanitized.
counters and sinks should be cleaned
room surfaces, including cage racks,
should be sanitized monthly.
animals must be identified according to
their protocol number, the name and phone
number of the investigator, species,
and should also include strain, sex, age and source.
- Rodents and smaller animals may be identified at the cage
or rack level. Large animals must have individual
is normally provided by a cage card, with
additional marking of individual animals
when needed. Groups of animals may be
identified using one posting if all
information is identical.
major consideration is the provision of
enough space to allow an animal to make
normal postural adjustments and have
normal intraspecific interactions
- Cage space
requirements are specified by
federal guidelines and law. Exceptions must be approved by the IACUC.
- For mice,
a standard "shoebox" type cage
can hold 4 adult female mice or 5 adult male mice and the larger rat shoebox cage can house
2 adult rats (3 if each is less than 500 g).
For other species enclosures should be
measured and the animals weighed to
determine if requirements are being met.
ultimate measure of whether or not cage
space is adequate is the condition of the
animal. If animal waste is excessive, or
if significant aggression is occurring,
the cage is too crowded.
- Type of
type floors are generally used for large
animals and rabbits for sanitary reasons.
Solid floors may be necessary if the
grate causes foot or leg problems.
bottom caging with bedding is the
preferred type of caging for all rodents.
Rodents over 600 g must have solid bottom caging,
unless a wire bottom is necessary for
scientific reasons. [Link to
mammals must have a solid floor at least
in a nest box, bedding and additional
animals, or animals to be maintained
specific-pathogen free may
require housing that has been sterilized,
usually by autoclaving.
- SPF rodents are usually housed in filter top
caging to prevent transmission of
diseases into or out of the cage. These
cages must be handled in protective hoods
using sterilants for anything that will
touch the interior of the cage.
material should be clean, dry, dust-free,
absorbent, non-toxic and preferably soft.
bedding used for rodents include hardwood
chip or ground corncob. Do not use aromatic
softwood (e.g. cedar) bedding material.
must be changed when it is visibly wet.
should be group housed with same-sex
conspecifics whenever possible.
housed animals must be assessed for
compatibility and separated if there is
significant aggression. If animals are
excluding others from food or water,
additional feeders and waterers must be
must be justified on the animal use
breeding protocols should be followed.
Attention should be paid to maintenance
of genetic homogeneity (inbred animals)
or heterogeneity (outbred animals).
Genetic monitoring may be necessary for
large or long-term breeding programs.
space requirements must be closely
monitored for breeding animals. Because
many laboratory mammals have large
litters and rapid growth rates, usually
no more than one breeding pair per cage
is appropriate. Animals should be weaned
before puberty and separated into
same-sex groups based on adult maximum
require environmental enrichment to allow
them to express normal specific
can include group housing or other
opportunities to socialize such as
visual, tactile or olfactory contact with
other animals, human interaction,
exercise opportunities, nesting material,
digging or chewing substrates, food
enrichment or other activities that
result in a positive psychological state
for the animals.
- RAR's Animal Enrichment Program can be viewed here.
- Cages may
be sanitized in a commercial cage
washer with a soap wash and a
high temperature (1800F) rinse.
This service can be contracted
- Cages may
be hand washed with detergent,
rinsed in water, then dipped in a
sanitizing agent (1/2 oz bleach
per gallon of water) and allowed
- Cages and
waste pans should be sanitized
weekly, or more often if
efficacy of sanitation procedures
should be monitored at least
quarterly. This service is
available through RAR.
of cleaned equipment.
- Animal food must supply
all required nutrients unless the requirements of the study
- Animals should
be fed commercially available complete diets appropriate
for their physiologic status.
- Rodents normally
are fed a pelleted chow, which helps to wear down continuously
erupting teeth. If powdered diets are to be fed a chewing substrate
may be necessary, or tooth growth must be monitored.
- Animals should be fed amounts
of food to provide at least their maintenance requirements.
The National Research Council publishes nutritional requirements
for most animals. These are also available through RAR. [Nutrient requirements
for laboratory animals; Dogs; Cats; Rabbits; Nonhuman Primates; Swine; Sheep; Poultry; Fish and Shrimp]
- If food is restricted
for more than 8 hours for neonates, rabbits or rodents, 48 hours
for ruminants, or 24 hours for other animals:
- For experimental reasons
this must be approved by the IACUC, written criteria
for assessing the animals body condition must be provided.
- For medical reasons this
decision should be made with veterinary input.
- Quality Control
- Commercially prepared food
must be used within 6 months of its milling date
(usually printed on the bottom of the bag).
- Specially formulated diets
may not have an expiration date. Generally these should be refrigerated
and used within 6 months of manufacture.
- Quality control or nutritional
analysis data should be obtained from the food manufacturer. If
diets are prepared in-house, nutritional analysis should be performed
following mixing and again at a later time point to determine the
amount of degradation over time.
- Food should be stored in
sealed, sanitizable containers. The type of food and expiration
date should be marked on the container. Containers should be cleaned
out weekly and sanitized monthly.
- Food should not be stored
adjacent to animal waste containers or chemicals.
- Sterilized food should be
stored in sterilized containers and the date of sterilization marked
on the container.
most purposes tap water from a potable
water faucet is adequate for research
experimental reasons, animals may have
special water requirements, such as a
need for deionized water, for sterilized
water, or for water treated with
animals should have drinking water
available at all times.
water is restricted for more than 24
hours for large animals, or 5 hours for
rodents or rabbits:
experimental reasons this must be
approved by the IACUC and
objective, written criteria for
assessing the animals
hydration must be provided.
medical reasons this decision
should be made with veterinary
potable tap water, quality control beyond
that which the municipality provides is
not usually necessary.
water needs may require additional
monitoring. Water may need to be analyzed
for chemicals or cultured for
The information contained in this site is
intended as a reference for University of Minnesota
investigators, and animal husbandry and veterinary staff.
Drug information and dosages are derived from a variety
of sources and do not necessarily guarantee safety or
efficacy. Information obtained through this site should
not be relied upon as professional veterinary advice. Any
medications administered or procedures performed on
animals should only be performed by or under order of a
qualified, licensed veterinarian.