Overcrowded Rodent Cages & Unidentified Animals

The housing of mice must not exceed a density greater than recommended by the 1996 NRC "Guide for the Care and Use of Laboratory Animals", unless approved by the Institutional Animal Care and Use Committee. This overcrowding policy clarifies standards and procedures to help ensure compliance with the Guide.

Overcrowding is defined as more than 5 adult mice (mice over 21 days of age) per cage. Because of different sized cages, all cages will be measured and the Guide standards will apply.

• Several smaller mouse boxes may be used to house a maximum of 4 adult mice per cage or a female with one litter of unweaned mouse pups.
• For paired breeding conditions, a breeding pair with a litter per cage is the maximum allowed.
• Under harem breeding conditions, a mouse box containing more than one pregnant mouse, with a visibly extended abdomen, is considered overcrowded. This is necessary to prevent two litters in one mouse box.
• Boxes with more than one litter are considered overcrowded.

When cages are observed as overcrowded, they will be marked with an "Overcrowded Cage" card and the vivarium supervisor and responsible faculty are notified. After the overcrowding has been corrected, the individual that corrected the overcrowding signs and dates the card and returns the card to the OCV office.

• Removal of this card, prior to correcting overcrowding, is a serious problem and will be dealt with accordingly.

• The OCV staff will separate the mice if the overcrowding is not corrected by 10:00 A.M. on the 4th day following the day the cage was marked as 'overcrowded". The OCV staff will adjust the census, duplicate the cage card, and identify the new cage with a card indicating the date the overcrowding was corrected.

• While every effort will be made by the OCV staff to duplicate and identify separated animals correctly, their only mission in this instance is to ensure that full compliance with federal mandates is maintained. Should an investigator fail to rectify one or more overcrowded cages, the OCV assumes no liability whatsoever in the maintenance of research data on the affected animals cage card.

• There will be a $25.00 service charge per incident levied against the responsible faculty via the Office of Research. If there are more than three boxes at one time, there will be an additional charge of $5.00 per box. If a responsible faculty member has more than 3 incidents in a 30-day period, the OCV will report this to the IACUC for any further action.

Unidentified Animals or Cages of Animals

All animals used for biomedical research, teaching or testing must be identified (usually with cage cards) with basic information as to faculty name, IACUC number, etc. Cages or pens containing animals that are not identified with appropriate vivarium cage cards will have an "Unidentified Cage" light cage card placed on the cage.

Vivarium managers and responsible faculty members are notified and are given until 10:00 A.M. on the 4th day following the placement of the card on the unidentified cage to complete the animal identification process.

After 10:00 A.M. on the 4th day, the Investigator will be notified again by phone/email about the unidentified cage. If no corrections are made within one business day following the phone call, a $25.00 service charge will be assessed to the responsible faculty member, and the OCV staff will step in to help identify the involved animal(s).

If the owner of the animal(s) cannot be identified and/or there is no approved use for the animal(s), the OCV in cooperation with the vivarium manager will determine the most appropriate action.