How many mice can I house per cage?

DLAR Policy for The Maximum Number of Mice Housed Per Cage

The ILAR Guide for the Care and Use of Laboratory Animals has guidelines for the maximum number of animals that can be legally housed per cage. Overcrowding of mice is in violation of these guidelines, and can jeopardize the University's AALAC accreditation status.

To assist investigators and DLAR staff in assuring that mice are not overcrowded, the following protocol must be followed:

1)      Standard mouse cages should house no more than 4 adult mice. Monogamous breeding pairs, or single pregnant females, should be placed in a large mouse breeding cage. Litters should be weaned at approximately 21 days of age.

2)    If a DLAR staff member find cages of mice that are overcrowded, the cage will be labeled and the investigator notified and asked to separate the animals.

3)      The investigator will be given 48 hours to correct the overcrowding problem.

4)      If the overcrowding problem has not been taken care of by the investigator the DLAR staff will separate the animals and transfer information from the old cage card onto a new cage card.

5)      If overcrowding is a recurrent problem with an investigator, the animal caretaker will notify their supervisor and/or a DLAR veterinarian.