Housing and Husbandry Guidelines for Laboratory Animals

The caging or housing system is an important factor in the physical environment of laboratory animals. They influence the well-being of the animals and act as experimental variables. 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 should be considered.

Checking Rooms

All animal rooms must be checked daily, including weekends and holidays, foul weather notwithstanding.
This check should include:
1. Monitoring room conditions
2. Monitoring for health problems
3. Monitoring food and water levels
4. Monitoring for proper cage conditions
5. Details of the needs for each of these items is provided below.
Problems should be evaluated based on the potential for adverse effects on the animals and remedied as soon as possible.
Documentation of daily checks should be provided in the form of a room Standard Operating Procedure (SOP), a log or a check list.

Room Conditions

General
1. An 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 include surgery, euthanasia and necropsy.
Light
1. Light 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.
2. The light cycle should be appropriate for the biology of the animal, if consistent with experimental goals. A diurnal 12 hour light cycle is standard. Reversal of the cycle or alteration of the cycle may be desirable depending on the experiment. Light cycles should be changed gradually, not abruptly.
Ventilation
1. Room ventilation 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 is desirable, although recycled air may be provided if it has been conditioned to remove excess heat, carbon dioxide, moisture, odors, or biological or chemical hazards.
2. Room ventilation should normally be adjusted to maintain room pressure negative to the corridor to protect adjacent personnel areas, or positive to the corridor if the room is serving as an isolation room.
3. Ventilation ducts and filters should be cleaned at least monthly.
Temperature
1. Temperature in rooms should be maintained in a range suitable for the species of animal and the animals should be protected from abrupt changes.
2. A range of 68° F to 74° F is standard for mammals.
3. Ectotherms and birds may have different needs. Animals adapted to outdoor environments may have different needs.
4. Temperature ranges for many animals are specified in the Animal Welfare Act.
Noise
1. Animals may detect different sound frequencies than do human beings. Therefore, noise in animal rooms should be minimized whenever possible.
2. Normally, playing music is not advisable in animal rooms, although it may be necessary under some circumstances to provide enrichment or "white noise" (to mask a different noise).
3. Quiet species should not be housed with noisy species.
4. Noise from mechanical equipment in adjacent areas should be avoided.
5. Some species may experience reproductive problems when exposed to excessive noise.
Sanitation
1. Room surfaces should be constructed of material that is easily sanitized.
2. Floors, counters and sinks should be cleaned sanitized daily.
3. Other room surfaces, including cage racks, should be sanitized monthly.

Cage Conditions

Identification
1. All animals must be identified according to their protocol number, the name and phone number of the investigator, species, strain, sex, age and source.
2. Rodents and rabbits may be identified to the cage level. Large animals must have individual identification.
3. Identification 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.
Cage Space Requirements
1. A major consideration is the provision of enough space to allow an animal to make normal postural adjustments and have normal intraspecific interactions (including avoidance).
2. Cage space requirements are specified by law, and must be closely adhered to.
3. Generally, a standard "shoebox" type cage can hold 4-5 adult mice (5 if they are less than 25 g) and a rat shoebox cage 2-3 adult rats ( 3 if less than 500 g). For other species cages should be measured and the animals weighed to determine if requirements are being met.
4. The 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 Caging
1. Grate 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.
2. Solid bottom caging with bedding is the preferred type of caging for all rodents. Animals over 600 g must have this type, unless a grate is necessary for scientific reasons. [Link to rationale]
3. Breeding animals must have a solid floor at least in a nest box, bedding and additional nesting material.
4. Immunodeficient animals, or animals to be maintained specific-pathogen free or gnotobiotic may require housing that has been sterilized, usually by autoclaving.
5. Some animals may require housing 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.
Bedding Material
1. Bedding material should be clean, dry, dust-free, absorbent, non-toxic and preferably soft.
2. Typical bedding used for rodents include hardwood chip, ground corncob, shredded paper or paper matting. Do not use aromatic softwood (e.g. cedar) bedding material.
3. Bedding must be changed when it is visibly wet.
Social Behavior
1. Animals should be group housed with same-sex conspecifics whenever possible.
2. Group 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 provided.
Breeding
1. Breeding must be justified on the animal use protocol. Need is based on scientific need or lack of availability of commercial sources, not on cost or convenience.
2. Standard 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.
3. Cage space requirements must be closely monitored for breeding animals. Because many laboratory species 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 weights.
Enrichment
1. Animals require environmental enrichment to allow them to express normal specific behaviors.
2. Enrichment 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.
Sanitation
1. Methods
  1. Cages may be sanitized in a commercial cage washer with a soap wash and a high temperature (180 ?F) rinse. This service can be contracted with RAR.
  2. 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 to dry.
2. Frequency
  1. Cages and waste pans should be sanitized weekly, or more often if required.
3. Quality Control
  1. Rinse water temperatures for automatic cage washers should be monitored via the gauge on the machine at least daily and with a thermometer or heat sensitive indicator at lease weekly.
  2. The efficacy of sanitation procedures at should be monitored at least quarterly. This service is available through RAR.
    1. General procedures include bacteriological culture of equipment and rinse water (for an automatic cage washer).
    2. Any cultures positive for non-spore forming organisms should be repeated. If subsequent testing is still positive then cage washing procedures must be assessed and modified.
  3. Autoclave efficacy is monitored daily using temperature/pressure indicators and quarterly using Bacillus spore strips. Any positive cultures should be repeated. If subsequent testing is positive, the autoclave must be serviced.

Food

Type
1. Animal food must supply all required nutrients unless the requirements of the study preclude it.
2. Normally, animals should be fed commercially available complete diets appropriate for their physiologic status.
  1. Growing animals, lactating animals, and animals experiencing physiologic stress such as surgical recovery, sepsis or hypothermia may require additional energy, protein or other nutrients.
  2. Animals with digestive abnormalities may require more highly digestible food, or may require more fiber.
  3. Animals with renal insufficiency may require lower dietary protein levels.
  4. Animals with blood glucose abnormalities may require additional fiber in their diet.
  5. Animals with pancreatic insufficiency will require enzymatic supplementation.
3. 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.
Amount
1. 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; Swine; Sheep; Poultry]
2. If food is restricted for more than 3 hours for neonates, rabbits or rodents, or 48 hours for ruminants, or 24 hours for other animals:
  1. For experimental reasons this must be approved by the IACUC and objective, written criteria for assessing the animals’ body condition must be provided.
  2. For medical reasons this decision should be made with veterinary input.
Quality Control
1. Commercially prepared food should only be used if it is within 6 months of its milling date (usually printed on the bottom of the bag). Diets with labile supplements (such as Vitamin C in nonhuman primate or guinea pig chow) have a shorter expiration time.
2. Specially formulated diets may not have an expiration date. Generally these should be refrigerated and used within a year of manufacture.
3. 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.
4. 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.
5. Food should not be stored adjacent to animal waste containers or chemicals.
6. Sterilized food should be stored in sterilized containers and the date of sterilization marked on the container.

Water

Type
1. For most purposes tap water from a potable water faucet is adequate for research animals.
2. For experimental reasons, animals may have special water requirements, such as a need for deionized water, for sterilized water, or for water treated with medications.
Amount
1. Generally, animals should have drinking water available at all times.
2. If water is restricted for more than 24 hours for large animals, or 5 hours for rodents or rabbits:
  1. For experimental reasons this must be approved by the IACUC and objective, written criteria for assessing the animals’ hydration must be provided.
  2. For medical reasons this decision should be made with veterinary input.
Quality Control
1. For potable tap water, quality control beyond that which the municipality provides is not usually necessary.
2. Special water needs may require additional monitoring. Water may need to be analyzed for chemicals or cultured for microorganisms.

Health Monitoring

Frequency
1. Animal health status must be monitored at least once daily, including weekends and holidays, foul weather notwithstanding.
2. Animals 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 frequent monitoring.
Clinical Signs of Disease
1. Clinical signs of disease can be extremely variable depending on the species of animal and the condition being monitored.
2. Changes in behavior, food or water consumption, fecal or urine output, reduction in grooming behavior, aggression, muscular rigidity, reaction to handling can be nonspecific signs of distress or disease.
3. More specific signs or objective measurements of organ dysfunction should be monitored if indicated by the animal’s condition or the expected impact of the experiment.
4. Further information is available from RAR.
Veterinary Care
1. All animals used for research, testing or teaching at the University of Minnesota must have an attending veterinarian listed on the protocol.
2. Veterinary care must be available on holidays and weekends as well as during work hours.
3. Research Animal Resources can provide veterinary consultation on request.

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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.