Care of Immunodeficient Mice and Rats

Immunodeficient rodents require special husbandry and housing in order to remain healthy and provide optimum experimental performance. Below are recommendations for care and housing of immunodeficient rodents.

Upon Delivery of Immunodeficient Rodents

Most facilities receive multiple animal deliveries on the same day. These shipments carry rodents of varying strains and health status.

• Rather than unpacking deliveries randomly, Taconic Biosciences recommends sorting transit cages based on immune status and health standard.
• Unpack immunodeficient animals first, then move to immunocompetent animals at higher health status and finally immunocompetent rodents at lower health status.
• Unpacking should occur in a cage change station or biosafety cabinet. Unpack immunodeficient animals from the transit cage directly into the housing cage.

Housing and Husbandry of Immunodeficient Rodents

• Immunodeficient animals should be housed in the cleanest portion of the animal facility. Ideally, they are housed in a separate room from immunocompetent animals. If this is not possible, personnel should finish work with immunodeficient animals before working with immunocompetent animals.
• All materials that contact immunodeficient animals should be sterilized, ideally through steam sterilization. This includes cages, bedding, water and feed.
• Taconic does not recommend prophylactic antibiotic treatment of immunodeficient animals for many reasons, including concerns about increasing antibiotic resistance and intestinal dysbiosis.
• Microisolator housing, for example, individually ventilated cages, should be employed. Using proper decontamination procedures between the changing of cages is recommended. One such approach is to use forceps that are disinfected before use with each new cage to pick up the tail of the mouse.
• Personnel movement policies are important to reduce the chance of contamination. The most desirable arrangement is to have dedicated personnel for the immunodeficient room. If separate technicians are not available, personnel should enter the room housing immunodeficient animals prior to entering areas housing immunocompetent animals. They should not return to the immunodeficient room during the same day unless proper personnel decontamination procedures have taken place.
• Cage servicing and experimental manipulations should occur in a hierarchy. Work in order of increasing immune function and practice aseptic technique.

Health Monitoring Best Practices

• Microbiological monitoring should be performed regularly, including monitoring of opportunistic agents.
• Heterozygous nude mice and rats are NOT recommended for use as sentinels as they do not have completely normal immune function.

Co-housing with Immunocompetent Rodents for Syngeneic Tumor Experiments

• If immunocompetent inbred mice used for syngeneic tumor studies are housed in the same location as immunodeficient mice, work with the immunodeficient animals first. We recommend syngeneic animals be sourced from more restrictive health standards so as not to carry in opportunistic agents of concern to immunodeficients.

Control Considerations

• When performing experiments comparing immunodeficient and immunocompetent animals of the same genetic background, source both experimental groups from the same vendor and health standard.

Experimental Procedures

• When transporting animals outside of the housing location to a procedure room, place animals into a microisolator cage for transit. A secondary container may also be advisable.
• If equipment must be shared for use with both immunodeficient and immunocompetent animals, be sure to disinfect equipment between uses. Work with the immunodeficients first, then the immunocompetents.

Contact Taconic for any questions regarding the above recommendations. Requirements for care will vary by facility. Please consult your veterinarian or facility manager for more information on working with immunocompromised animals.