IACUC Policy on Animal Housing and Enrichment

Overview

The primary aim of environmental enrichment is to enhance animal well-being by providing animals with sensory and motor stimulation, through structures and resources that facilitate the expression of species-specific behaviors and promote psychological well-being through physical exercise, manipulative activities, and cognitive challenges according to species-specific characteristics. ¹ Federal animal welfare regulations also provide specific requirements to meet the enrichment and exercise requirements for non-human primates ² and dogs ³, respectively.

Definitions

Standard housing refers to the type(s) of housing approved by IACUC and provided by ULAR for general use (varies by species).

Environmental enrichment refers to additions to an animal's environment with which it can interact. The goal is to allow animals to express a range of species-typical behaviors which may enhance their well-being. Examples of environmental enrichment include:

Group housing of compatible animals
Providing animals with a means for control over their environment (e.g., nest-building materials, hiding places)
Novel items (e.g., toys, special food treats)
Opportunity for exercise (e.g., running wheels, climbing structures)

The appropriateness of specific environmental enrichment is determined by the species used, type of housing, space available, research needs, standard husbandry practices and other operational issues.

Policy

Social Housing

The Guide¹ states that single housing of social species should be the exception. Social housing will be considered by the IACUC as the default method of housing unless otherwise justified based on social incompatibility resulting from inappropriate behavior, veterinary concerns regarding animal well-being, or scientific necessity approved by the IACUC. Social species maintained at UCI include all mice, rats and cats. When necessary, single housing of social animals should be limited to the minimum period necessary. Common exceptions to social housing are:

Any animal that has demonstrated aggression/fighting behavior, or animals known to have a propensity for fighting (e.g., male mice, male rabbits, female hamsters).
Breeders not currently in use.
When a companion animal is not available (e.g., a single animal of a particular sex at weaning, or the last animal remaining in an experimental cohort.
Animals in the immediate post-surgical period (i.e., when sutures are present); however, animals must be returned to social housing agaiin after suture removal.
Scientific necessity as reviewed and approved by the IACUC.

Environmental Enrichment

To provide for the physical and social needs of research animals, the IACUC requires that appropriate environmental enrichment be provided as part of standard animal housing unless there is scientific justification, approved by the IACUC that precludes the use of environmental enrichment materials or practices. This policy outlines the types of standard housing used for laboratory animal species at UCI and the types of environmental enrichment materials or practices that may be used to enhance species-specific behavior and reduce distress and anxiety in laboratory animals.

Implementation

All animals housed for use in research, teaching or testing purposes at UCI must be housed in an animal facility or other space approved by the IACUC.
Each animal housing room (or isolated housing unit) will contain a single species unless special housing arrangements have been made with ULAR for compatible species.
Standard housing is provided by ULAR on a recharge basis, unless the IACUC has approved that housing can be provided and maintained by research groups. For certain species of animals that are not currently or routinely housed at UCI, research groups may be responsible for set-up costs to provide specialized equipment for maintaining the animals.
Changes to the standard housing and environmental enrichment described in Table 1 below are not permitted except under the following circumstances:
- Changes are described in the animal use protocol and approved by the UCI IACUC.
- Changes are prescribed by the ULAR Veterinary Services group for animal health or welfare reasons.
Enrichment materials or practices should not significantly alter the species-appropriate standards for husbandry, nutrient requirements or housing, as described in The Guide, unless these deiations are described and approved by the IACUC in the animal use protocol.
Provision of environmental enrichment other than the Standard or Allowed Environmental Enrichment described in Table 1 must be described in the IACUC protocol. If the standard housing and enrichment for the species cannot be used, a justification must be submitted and approved by the IACUC.
For USDA-covered species, a written record of the environmental enrichment items provided will be kept along with the daily husbandry records

Table of Standard and Additional Enrichment

Species (common name)	Standard Housing	Standard Environmental Enrichment Required (ULAR-Provided)	Additional Enrichment Allowed/Recommended (Research Group Must Provide)
Mice	Solid-bottom plastic cage with a wire bar lid that serves as a food hopper and water bottle holder. Filter top (microisolator lid). Cages may be placed on ventilated racks providing filtered air directly to the cage, or placed on static racks. Water bottle. Contact bedding consisting of commercially-available corn cob particles, wood chips, cotton, or paper products specifically made for laboratory animals. Commercially-available laboratory rodent diets approved by ULAR.	Group-housed if compatible (e.g. adult males from different litters cannot be housed together). Nesting material made from paper or cotton fibers. (e.g. Nestlets). For Lab Products® cages without a wire bar, provide a plastic loft or mouse hut	Disposable cardboard mouse houses ("Shepherd Shacks") Plastic mouse houses (must be cage-washer safe).
Rats	Solid-bottom plastic cage with a wire bar lid that serves as a food hopper and water bottle holder. Filter top (microisolator lid) may be used. Cages may be placed on ventilated racks providing filtered air directly to the cage, or placed on static racks. Water bottle. Contact bedding consisting of commercially-available corn cob particles, wood chips, cotton, or paper products specifically made for laboratory animals. Commercially-available laboratory rodent diets approved by ULAR.	Group-housed if compatible. Nesting material Plastic rat "houses" or tubes	Sterilized wooden tongue depressors for chewing. Sterilized Nyla bones for chewing.
Rabbits	Sanitizable cage of appropriate size with suspended floor. Water bottle or lixit for automatic watering. Commercially-available laboratory rabbit chow approved by ULAR.	Group-housed if compatible Sanitizable toys such as plastic chains or balls, stainless steel rings, PVC pipe; rotated weekly. Small portions of timothy hay, other grass hay, alfalfa hay, fresh spinach or fresh kale offered one to three times per week in a sanitizable feeder, or on cage bottom.	Small amounts of other fresh vegetables such as carrots and Romaine lettuce. Small amounts of dried banana chips apples or pineapple.
Pigs	Indoor pens with sanitizable surfaces. Lixit for automatic watering. Wood chip contact bedding in solid bottom pens. Sanitizable food bowls. Nutritionally complete commercially available diet for laboratory pigs approved by ULAR.	Group-housed if pen size is adequate and if animals arrive together and are compatible. Social contact with other pigs if possible. Sanitizable toys (e.g. Kong(R) toys, plastic balls).	Small amounts of food treats such as fresh vegetables, yogurt or fruit. Positive human interaction (e.g. scratching back) if pigs are acclimatized to this.
Cats	Housed in large indoor holding rooms in compatible groups. Space allocation is at least the minimum required by Animal Welfare Act. Cats may be housed in smaller individual cages temporarily (e.g. after surgery). Sufficient litter boxes appropriate for the number of cats. Fresh water in sanitizable bowls. Nutritionally complete, commercially available dry cat food approved by ULAR. • Group-housed if compatible.	Group-housed if compatible. Positive human interaction daily (e.g. patting, scratching, rubbing back). Multi-level shelves for resting and climbing. Sanitizable or washable toys and items such as scratching posts, toy mice and balls.
Guinea Pigs	Polystyrene, polycarbonate or other high-temp plastic solid bottom cage with a wire bar lid that serves as a water bottle holder. Contact bedding consisting of commercially-available corn cob particles, wood chips, cotton or paper products specifically made for laboratory animals. Alternatively, cages with suspended, slotted floor. Filter top (microisolator lid) may be used. Cages may be placed on ventilated racks providing filtered air directly to the cage, or placed on static racks. Water bottle. Sanitizable food bowl. Commercially-available laboratory guinea pig diets approved by ULAR.	Group-housed if compatible. Small quantities of Timothy or alfalfa hay 2 to 3 times per week.	Plastic guinea pig houses (must be cage-washer safe). Disposable cardboard guinea pig houses ("Shepherd Shacks"). Sanitizable toys such as balls or Kong toys.
Hamsters	Solid-bottom plastic cage with a wire bar lid that serves as a food hopper and water bottle holder. Filter top (microisolator lid). Cages may be placed on ventilated racks providing filtered air directly to the cage, or placed on static racks. Water bottle. Contact bedding consisting of commercially-available corn cob particles, wood chips, cotton, or paper products specifically made for laboratory animals. Commercially-available laboratory rodent diets approved by ULAR.	Group-housed if compatible. Nesting material made from paper or cotton fibers.	Disposable cardboard hamster houses ("Shepherd Shacks") Plastic hamster houses (must be cage-washer safe).
Gerbils	Solid-bottom plastic cage with a wire bar lid that serves as a food hopper and water bottle holder. Filter top (microisolator lid). Cages may be placed on ventilated racks providing filtered air directly to the cage, or placed on static racks. Water bottle. Contact bedding consisting of commercially-available corn cob particles, wood chips, cotton, or paper products specifically made for laboratory animals. Commercially-available laboratory rodent diets approved by ULAR.	Group-housed if compatible. Nesting material made from paper or cotton fibers.	Disposable cardboard gerbil houses ("Shepherd Shacks") Plastic gerbil houses (must be cage-washer safe).
Birds	Sanitizable wire cages or large flight cages. Perches. Fresh water in water bottle or sanitizable bowls. Food containers and water bottles should be designed and positioned to minimize fecal contamination. Shelter from sun, rain and extreme weather conditions if housed in outdoor aviaries. Nutirionally-complete food appropriate for the species. Dietary supplements appropriate for the species (e.g. cuttlefish bones, shell grit, fresh greens).	Group-housed if compatible. Mirrors if housed singly. Nesting materials and enclosures for breeding.	Sanitizable mirrors, swings, ladders, or other types of perches as appropriate for the species.
Xenopus	Aquaria made of sanitizable materials. Static or flow-though water system. Water filtered or conditioned to remove/inactivate chlorine and chloramine. Nutritionally-complete commercially-available food.	Group-housed if compatible. Shelter structures such as plastic guinea pig houses or large PVC pipes to allow frogs to hide.	Small amounts of dietary supplements such as blood worms, chopped beef heart, and chopped liver.
Fish	Aquaria made of sanitizable materials. Static or flow-though water system. Water filtered or conditioned to remove/inactivate chlorine and chloramine. Nutritionally-complete fish food appropriate for the species.	Group housed if compatible.
Reptiles	Sanitizable, secure enclosures of appropriate size and configuration for the species. Opportunity for animals to thermoregulate, or a constant temperature range in the thermoneutral zone for the species. Water and nutritionally complete food appropriate for the species.	Sanitizable objects to provide hiding places.
Sheep	Housed indoors in appropriate pen. Nutritionally complete, commercially available pelleted feed, approved by ULAR Hay Fresh water	Group-housed if compatible Stainless steel mirror if single-housed

References

¹ Guide for the Care and Use of Laboratory Animals (National Academies Press, 2011), page 52.
² Animal Welfare Regulations, 9 CFR Chapter 1, Part 3, Subpart D, Section 3.81
³ Animal Welfare Regulations, 9 CFR Chapter 1, Part 3, Subpart A, Section 3.8