Basic Biomethodology
For Laboratory Mice

The Public Health Service Policy on Humane Care and Use of Laboratory Animals and the Animal Welfare Act require institutions to ensure that people caring for or using animals are qualified to do so.

Institutions base their animal care and use program on the Guide for the Care and Use of Laboratory Animals, also referred to as the Guide. This CD represents one component of the comprehensive training program offered by the NHGRI Office of Laboratory Animal Medicine to meet the Guide specifications on the training of personnel.

The following principles, described in the Guide, apply to basic biomethodology for laboratory mice: personnel caring for animals should be appropriately trained. The institution should provide for formal or on-the-job training to facilitate effective implementation of the program and humane care and use of animals.

Entrance Procedures

Access to most NIH animal facilities is by card-key and/or punch pad access codes.

They are for the sole use of the person to whom it was issued.

Card keys and access codes are not to be shared. Sharing of personal codes or card keys could result in termination of your access privileges.

Animal users are not provided with access to the animal facility until all training requirements are met.

When traveling between multiple animal housing areas, the veterinarian should be consulted for the proper traffic pattern to avoid the possibility of cross-contamination between facilities.

A shower and change of clothes may be required before entrance is allowed into a second facility.

Equipment and supplies should not be transported between facilities or from the lab to the vivarium without undergoing proper disinfection.

There are several choices of disinfection procedures, which include spraying down with Clidox or another similar disinfectant, ethylene oxide sterilization, steam autoclaving or cold sterilization.

You should consult your veterinarian for the proper selection of disinfection procedures.

Personal Protective Equipment

All animal facilities require some level of protective clothing in order to protect the animals housed within from contaminants that may enter the facility via the personnel and to protect the personnel from exposure to animal allergens or other potential hazards.

Examples of protective clothing are lab coats, jumpsuits, shoe covers, hair bonnets, masks and gloves.
Revised 4/6/04 2

In most cases, entry requirements are posted on the facility or animal room doors. If you have questions, you should contact the facility veterinarian.

Microisolator Technique

It is your responsibility to become familiar with facility requirements prior to beginning any animal work.

Some facilities require that all animal cages be opened inside a biosafety cabinet. In this case, the cages are sprayed with disinfectant prior to placing them in the cabinet and prior to removing them from the cabinet. Hands are sprayed with disinfectant prior to handling the cage and again prior to handling the cage contents.

Other facilities manipulate the cages on a cart or bench top and use a modified microisolator technique. In this case, the cage and the gloved hands are sprayed with disinfectant. The microisolator lid is removed and placed inverted on the bench or cart. The hands are sprayed with disinfectant again. The wire bar lid is removed and placed on the inverted microisolator top. The mice are transferred. Disinfection of the gloved hands is repeated between each cage.

Make sure the disinfectant is allowed to drain from the gloved hands so that excessive amounts of disinfectant do not come into contact with the animal.

Disinfectants used for microisolator technique vary between facilities.

Assessing the General Health of Mice
A brief assessment of the health of every animal should be conducted prior to performing any technical procedures.

The animal should be observed for signs of illness including

• ocular or nasal discharge
• rough hair coat
• abnormal posture
• uterine, rectal or penile prolapse
• limb abnormalities
• abdominal distension
• malocclusion
• dehydration
• dystocia, or
• abnormal behavior.

Any signs of pain or distress should be reported immediately to the veterinarian, using the reporting procedures established by the animal facility Standard Operating Procedures.

Any animal welfare concerns should also be reported immediately via the appropriate channels.

Observe the feed and water supplies to ensure that there is evidence that the animal has been eating and drinking.

Mice are social animals and should be housed in compatible groups.

However, group-housed males will often fight.

They should be observed closely for fight wounds and separated immediately if fighting is noted.

Barbering may also be seen in group-housed mice of both sexes.

The muzzle and other areas of the body are shaved by the dominant mouse in the cage.

Removing the dominant animal may stop the behavior, but frequently another mouse assumes the role.

It is important that every animal handler be properly trained to distinguish between male and female mice.

The anogenital space is almost twice as long in the male as it is in the female.

Male mice also lack nipples.

It is more difficult to differentiate the sex of neonatal mice.

Sometimes it is helpful to compare two animals side by side for a reference point.

Mice are nocturnal.

Mice also exhibit strong burrowing and nesting behavior and should be provided with bedding materials, such as Nestlets, that encourage this activity.

Other environmental enrichment devices should also be utilized, as appropriate.

Some examples include paper or plastic tubes, igloos, food treats and chew toys. All enrichment devices must be approved by your veterinarian prior to use.
Revised 4/6/04 3

Remember

• You have an ethical and legal responsibility to treat all animals in a humane manner.
• All personnel must be appropriately trained.
• You must adhere to all facility entrance requirements.
• Always use proper microisolator technique.
• Always consult your veterinarian if you need assistance.