Animal
Housing and Care
Four
principal documents that deal with
animal housing and care are:
- Title 9 CFR, Part 3 - Standards of
the Animal Welfare Act 1966 (PL
89-544), Amended 1970 (PL 91-579),
Amended 1976 (PL 94-279), Amended
1985 (PL 99-198).
- Guide for the Care and Use of Laboratory
Animals, NIH Publication No.
85-23, 1985.
- Standards for the Breethr management
of (Separate Volumes
for Various Species), NAS.
- Guide for the Care and Use of Agricultural
Animals in Agricultural Research and
Teaching, Consortium for Developing
a Guide for Care and Use of Agricultural
Animals in Agricultural Research and
Teaching, 1988.
The
following comments are extracted from
these documents and are intended to
provide a broad overview of important
components of animal care and use
programs.
The
Guide for the Care and Use of Laboratory
Animals states, “Proper management
of animal facilities is essential
to the welfare of animals, validity
of research data, and health and safety
of the animal care staff. A good husbandry
program provides a system of housing
and care that permits animals to grow,
mature, reproduce, and maintain good
health. Good husbandry minimizes variations
that can modify an animal’s
response to experimentation. Specific
operating practices depend on many
subjective and objective factors unique
to individual institutions.”
Animal
Housing
The
caging or housing system is one of
the most important elements in the
physical and social environment of
research animals. It should be designed
to facilitate animal care, meet research
requirements, and minimize experimental
variables. The housing system should:
- provide
space that permits freedom of movement
and normal postural adjustments and
which has a resting place appropriate
to the resting place appropriate to
the species;
- provide an escape-proof enclosure
that confines animals safely and prevents
access by predators and exposure of
animals to other hazards;
- provide a clean, comfortable environment
with easy access to food and water,
and meet the biological needs of the
animals, e.g., maintenance of body
temperature, urination, defecation,
and, if appropriate, reproduction.
The
effects of social environment on caged
animals are often more difficult to
define than the effects of physical
environment. Attention should be given
to whether the animals are naturally
territorial or communal in determining
whether they will be housed singly
or in groups. Consideration should
also be given to enriching the environment
as appropriate to the species, especially
when animals will be held for long
periods. Social factors can affect
reproduction, metabolism, immune responses,
and behavior.
There
are few critical and objective data
on space requirements for animals.
Recommended animal housing systems
are based on successful experience
and professional judgment. Minimum
space recommendations for animals
used in research, teaching and testing
are given in the documents listed
above and should be followed unless
there is satisfactory scientific justification
for providing less space.
Animals
maintained in a laboratory environment
have restricted activity. Unfortunately,
there are no unequivocal data relating
the quality or quantity of an animal’s
activity to its physical or psychological
well-being. The need for exercise
is subject to professional judgment
based on an understanding of species
or breed temperament, age, history,
physical condition, nature of the
research, and expected duration of
residence.
The
micro-environment of an animal is
the physical environment immediately
surrounding it within the cage or
other primary enclosure. The physical
conditions in the room or other secondary
enclosure constitute the macro-environment.
There may be differences between these
two environments in that temperature,
humidity, and concentrations of gases
such as carbon dioxide and ammonia
are often higher in cages (unless
they are individually ventilated)
than in the surrounding room. Exposure
of rodents to these conditions can
cause alteration of their biologic
responses and increase susceptibility
to infectious, toxic, and other harmful
agents.
Temperature
and humidity are important factors
in an animal’s physical environment
because they can affect metabolism
and behavior. The range of environmental
temperatures at which an animal’s
oxygen consumption is minimal is called
the thermoneutral zone. Recommended
dry bulb temperature ranges for optimal
development, comfort, reactivity,
and adaptability, generally are lower
than the reported thermoneutral zones.
Ranges of 40-70% R.H and 17-26oC
(64.4-78.8oF) encompass the recommendations
for laboratory housing of most mammals.
Rabbits should be kept at temperatures
between 16-21 oC (60.8-69.8oF); whereas
nude mice, newborn of many species,
and new world monkeys do better at
the high end of the range. Temperature
control and humidity should be monitored
regularly.
The
quality of an animal’s micro-environment
is determined by the effectiveness
of the ventilation system in maintaining
acceptable thermal conditions and
controlling contaminants within the
primary enclosure. Experience has
shown that 10 to 15 room air changes
per hour using 100% fresh air appears
to provide adequate ventilation for
animal facilities. Other methods of
providing equal or more effective
ventilation may also be acceptable.
Room air in animal facilities should
not be recirculated unless treated
to remove particulate and toxic gaseous
contaminants. Mechanical systems that
control the animal environment should
be monitored regularly.
In
animal facilities housing microbiologically-defined
animals or where hazardous agents
are used, relative air pressures between
animal housing and service areas should
be controlled. Contaminated areas
should be kept under relative negative
pressure with appropriate treatment
of exhaust air, whereas clean equipment
and pathogen-free animal housing areas
should be kept under relative positive
pressure.
Lighting
in animal facilities should be uniformly
diffused and provide sufficient illumination
to aid in maintaining good housekeeping
practices, adequate inspection of
animals, safe working conditions for
personnel, and the well-being of the
animals. Precise lighting requirements
for maintenance of good health and
physiological stability of animals
are not known. High light levels have
been shown to cause retinal damage
in albino mice and rats. Light levels
of 323 lux (30 ft-candles) approximately
1.0 m (3.3 ft) above the floor appear
to be sufficient for performance of
routine animal care. These levels
apparently do not cause retinal lesions
in albino animals. A time-controlled
lighting system should be used to
provide a regular diurnal lighting
cycle. Timer performance should be
checked periodically to ensure proper
cycling.
Noisy
activities such as cage washing and
refuse disposal should be carried
out in rooms or areas separate from
those for animal housing. Noisy animals,
such as dogs and some non-human primates,
should be housed away from rodents,
rabbits, and cats. Continuous exposure
to acoustical levels above 85 dB can
have both auditory and nonauditory
effects, including eosinopenia, increased
adrenal weights, reduced fertility,
and increased blood pressure.
Animal
Feeding, Watering and Bedding
Animals
should be fed palatable, uncontaminated,
and nutritionally adequate food daily
or according to their particular requirements,
unless the experimental protocol requires
otherwise. Feeders should allow easy
access to food, while minimizing contamination
by urine and feces. Food should be
available in amounts sufficient to
ensure normal growth in immature animals
and maintenance of normal body weight,
reproduction, and lactation in adults.
The choice of laboratory animal diet
will depend on animal requirements
and experimental objectives.
Laboratory
animal maintenance diets should not
be manufactured or stored in facilities
used for products containing additives
such as rodenticides, insecticides,
hormones, antibiotics, fumigants,
or other potential toxicants. Areas
in which diets are processed should
be kept clean and enclosed to prevent
entry of insects or other animals.
Bulk supplies of food should be stored
off the floor in designated, restricted
areas that are cool, dry, clean, and
free of vermin and other potential
contaminants.
The
length of time since manufacture and
other factors affecting shelf life
of food should be monitored. Most
natural-ingredient, dry laboratory
animal diets that are stored properly
can be used up to six months after
manufacture. Vitamin C contained in
food for nonhuman primates, and a
few other species, however, generally
has a shelf life of only three months.
Purified and chemically defined diets
are generally less stable than natural
ingredient diets, and their shelf
life is usually less than six months.
Bedding
should be absorbent, free of toxic
chemicals or other substances that
could injure animals or personnel,
and of a type not readily eaten by
animals. Aromatic hydrocarbons from
cedar and pine bedding materials can
induce the biosynthesis of hepatic
microsomal enzymes and may be inappropriate
for bedding animals used in some experiments.
Bedding should be stored off the floor
on pallets, racks, or carts.
Animals
should have continuous access to fresh,
potable, uncontaminated drinking water,
according to their particular requirements.
Some experimental and testing protocols
may require highly purified water.
Watering devices, such as drinking
tubes and automatic waterers, should
be examined routinely to ensure their
proper operation.
Sanitation
Sanitation
and good housekeeping are essential
in an animal facility. Animal rooms,
corridors, storage spaces, and other
areas should be cleaned with appropriate
detergents and disinfectants as often
as necessary to keep them free of
dirt, debris, and harmful contamination.
Cleaning utensils, such as mops, pails,
and brooms, may spread contamination
and should not be shared between animal
rooms.
Bedding
used in cages or pens should be changed
as often as is required to keep the
animals dry and clean. For routine
maintenance of small rodents such
as rats, mice, and hamsters, one to
three bedding changes per week may
suffice, while for larger animals,
such as dogs, cats, and non-human
primates, daily cleaning may be required.
Litter should be emptied from portable
cages or litter pans in an area other
than the animal room and in a manner
that minimizes exposure of animals
and personnel to aerosolized waste.
In some instances, such as when pheromones
are essential for reproduction or
to achieve certain research objectives,
exceptions to the regular cage-cleaning
schedule can be justified.
Animal
cages, racks, and accessory equipment,
such as feeders and watering devices,
should be washed and sanitized frequently
to keep them clean and free from contamination.
The use of mechanical equipment-washing
machines is highly recommended. The
machines should provide wash and rinse
cycles, preferably with adjustable
time settings for each. If sanitization
depends on heat for effectiveness,
the equipment should supply rinse-water
temperatures of at least 82.2oC (18OoF). Water bottles, sipper tubes,
stoppers, and other watering equipment
should be washed and then sanitized
using above temperatures or appropriate
chemical agents to destroy pathogenic
organisms.
Deodorizers
or chemical agents should not be used
to mask animal odors. Such products
are not a substitute for good sanitation,
and some have been shown to cause
metabolic changes that may interfere
with experiment results. Waste containers
and implements should be cleaned frequently.
It is good practice to use disposable
liners and to wash each waste can
frequently using the methods suggested
above for cages. All waste should
be collected and disposed of in a
safe and sanitary manner. Waste cans
should be metal or plastic, leak-proof
and equipped with tight-fitting lids.
Waste cans containing animal tissues,
carcasses, and hazardous wastes should
be lined with leak-proof, disposable
liners. If wastes must be stored before
removal, the waste storage area should
be separated from other storage facilities
and free of flies, cockroaches, rodents,
and other vermin. Cold storage may
be necessary to reduce decomposition
of biological wastes. Hazardous wastes
should be rendered safe by sterilization,
containment, or other appropriate
means before they are removed from
an animal facility.
Programs
should be instituted to control, eliminate,
or prevent infestation by pests such
as cockroaches, flies and wild or
escaped rodents. The most effective
programs depend on prevention of vermin
entry into the facility, sanitation,
and elimination of breeding and refuge
sites. Improper use of pesticides
can induce toxic effects in research
animals and interfere with experimental
procedures. Pesticides should be used
in animal areas only when necessary
and then only after consultation with
the investigator(s) whose animals
may be exposed to them. Application
of pesticides should be recorded and
coordinated with the animal care management
staff and in compliance with federal,
state, or local regulations.
Animal
Identification
Methods
of animal identification include room,
rack, and cage cards; collars, bands,
plates, and tabs; colored stains;
ear notches and tags; tattoos; and
freeze brands. Identification should
include such information as the source
of the animals, strain or stock, names
and locations of the responsible investigators,
and pertinent dates. Records should
include a history of surgical procedures,
experimental use, and pertinent clinical
and diagnostic information. The source
and eventual disposition of animals
is often valuable, and sometimes essential,
information which should be included
in individual records as required.
Emergency,
Weekend and Holiday Care
In
the event of an emergency, institutional
security personnel and fire or police
officials should be able to contact
persons responsible for the animals.
This can be accomplished by prominently
posting names and phone numbers in
animal facilities or by listing them
with the MU Campus Police.
Animals
should be observed and cared for by
qualified personnel every day, including
weekends and holidays, both to safeguard
their well-being and to satisfy research
requirements. A procedure should be
established for providing emergency
veterinary care after work hours,
on weekends, and on holidays. An OAR
veterinarian is on call every day.
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