OPERATING POLICY
ANIMAL RESOURCE CENTER
CASE WESTERN RESERVE UNIVERSITY
POLICY NUMBER: 042013-1
REVISION NUMBER: Original
EFFECTIVE DATE: 4/16/2013
TITLE: Policy on Mouse and Rat Breeding, Weaning and Housing Density
Prepared by: K. Brock, DVM
Authorized by: IACUC
Date: 4/13/2013
Date: 4/16/2013
Original Policy Issue Date: 4/16/2013
Document History:
Policy
Number
042013-1
Revision
Number
0
Description of Changes
Formatted SOP. JH
Date of
Revision
4/13/2013
1. Title: Policy on Mouse and Rat Breeding, Weaning and Housing Density
2. Purpose:
The purpose of this policy is to provide Animal Resource Center (ARC) staff, investigators and
research personnel with clearly defined parameters regarding housing capacity of mice of the
genus Mus and rats of the genus Rattus. In order to remain in compliance federal regulations
and AAALAC accreditation standards, mouse and rat housing density at Case Western Reserve
University (CWRU) and MetroHealth Hospital vivaria must be maintained within the limits
described in the Guide for the Care and Use of Laboratory Animals, Eighth Edition as outlined
within this policy.
3. Responsibilities:
It is the responsibility of all CWRU principle investigators and research personnel housing mice
and rats, as well as ARC animal care staff to abide by this policy. The CWRU Institutional
Animal Care and Use Committee and the ARC staff are responsible for enforcement of this
policy.
4. Definitions:
MMR: Morbidity/Mortality Report – the method by which the ARC animal care staff reports
animals with veterinary concerns to the veterinary staff and investigative staff. All MMR cards
regarding sick animals should be left on the cage while the animal(s) is/are under veterinary
care or observation.
Monogamous breeding (♂+♀): One male housed with a single female. Sire and dam are
housed together long-term.
Policy Number
042013-1
Revision
Number
0
Description of Changes
Formatted SOP. JH
Date of Revision
4/13/2013
1
Trio breeding (♂+♀♀♀): One male housed with 2 to 3 females. Each female is removed from
the group when pregnancy is confirmed and remains housed
separately until pups are weaned.
Harem breeding (♂+♀♀): One male housed with 2 females. The group stays together and both
females help care for the offspring.
Symbols:
= Female;
= Female with litter;
= Pregnant female;
|
♂ = Male;
= cage
!!!!!!
5. Policy:
i. Housing density may not exceed the minimum space recommendations in the Guide for the
Care and Use of Laboratory Animals, Eighth Edition.
 Exceptions may only be granted by the IACUC and must be included in the approved
animal use protocol.
 Any request for waiver of the housing density allowance outlined in this policy must be
accompanied by sufficient scientific justification. Convenience and cost savings do not
constitute acceptable justification.
ii. Housing density allowances for MICE (weanlings and adults):
Mouse weight
< 10 g
10–15 g
15–25 g
Ventilated cage
11
8
5
Static cage
11
8
5
Disposable cage
12
10
6
> 25 g
up to 4
up to 4
up to 5
iii. Housing density allowances for breeding MICE:
Monogamous Pair
Trio
Harem
♂♀
♂♀♀
♂♀♀♀
1 male and 1 female
1 male and 2 females
1 male and up to 4 females
Mice allowed per
breeding cage
♂
Mice allowed per
cage during
pregnancy
Both adults may stay
together throughout
the gestation period.
♂
Mice allowed per
cage following
parturition
Policy Number
042013-1
!!!!!!
♂
|
Only ONE (1) female may
remain with the male
throughout gestation, the
second female must be
removed from the cage
upon confirmation of
pregnancy.
♂ |
!!!!!!
!!!!!!
The male may stay with
ONE (1) female & litter,
Revision
Number
0
Description of Changes
Formatted SOP. JH
♂
|
|
Only ONE (1) female may
remain with the male
throughout gestation, all
others must be removed from
the cage upon confirmation of
pregnancy.
♂ |
!!!!!!
!!!!!!
|
!!!!!!
The male may stay with ONE
Date of Revision
4/13/2013
2
Both adults may stay
with the litter, but pups
should be weaned
prior to birth of
subsequent litter
iv.
(1) female & litter, but pups
should be weaned prior to
birth of subsequent litter.
Other females may be replaced with the male only
after pups are weaned.
Housing density allowances for compatible RATS (weanlings and adults):
≤ 250 g
5
Rat weight
All cages
v.
but pups should be
weaned prior to birth of
subsequent litter. Other
females may be replaced with the male only
after pups are weaned.
201–300 g
4
301–400 g
401–500 g
>500 g
3
2
1
Housing density allowances for breeding RATS (Only monogamous pairing is permitted):
♂♀
Breeding
1 male and 1 female
♂|
During pregnancy
Adults must be housed in separate cages prior to parturition
♂|
Following parturition
!!!!!!
Only ONE (1) female and her litter may be housed together
6. Procedures:
WEANING PROCEDURES
i. Mouse pups must be weaned at 21 days of age. Exceptions may be granted for strains with
pups that average smaller than typical size when approved by the IACUC and in the
investigator’s animal use protocol. Rat pups must be weaned at 21 days of age.
ii. All newly weaned mice should be provided with moistened food or dry food + hydrogel on
the floor of the cage for at least 1-3 days.
iii. Pups should be separated by sex at weaning.
OVERCROWD PROCEDURES (When the ARC staff identifies an overcrowded cage)
i. An MMR is completed and turned it in at the veterinary technician office.
ii. Information is entered into the MMR database and an email is sent to investigative staff
alerting to the overcrowded cage.
iii. Investigative staff is allowed 24 hours (emergency) or 48 hours (routine) from the time of the
email generation to separate the animals.
iv. After the appropriate time period, if the cage remains overcrowded, ARC staff separates
animals into 2 or more cages, as appropriate, on a fee-for-service basis.
Policy Number
042013-1
Revision
Number
0
Description of Changes
Formatted SOP. JH
Date of Revision
4/13/2013
3
Policy Number
042013-1
Revision
Number
0
Description of Changes
Formatted SOP. JH
Date of Revision
4/13/2013
4