Mouse breeding, weaning and necropsy SOP Starr Lab
Title or Type of Procedure: Mouse breeding, weaning and necropsy
P. I. Timothy K. Starr
Lab Location: 12-175 MoosT
Original Issue Date: 5/23/11
Prepared By:
Revision Dates:
5/23/11, 3/4/14
Timothy K. Starr Approval Signature:
(if required by lab supervisor)
Background:
Procedural Methods and Materials:
General Safety Procedures:
All laboratory personnel handling mice must be trained in Specific Pathogen Free (SPF) procedures
and must be listed on the IACUC protocol. See the RAR website for more information on
SPF training (http://www.ahc.umn.edu/rar/index.html). In general, SPF procedures require
that microisolator cages must only be opened in a laminar flow hood and should be handled
like a sterile petri dish. If the barrier is broken (cage left open, animal escapes and contacts
the floor, improper microisolator procedure, etc.) within an animal room, the investigator
should place a note on the cage indicating how the break occurred. RAR will handle these
animals last. If the break occurs outside of the animal room the animals must be euthanized
or placed into quarantine to assess their disease status before being allowed to return to the
colony. Animals that arrive in the facility with infectious diseases that are excluded must also
be quarantined until the diseases can be cleared.
When transporting mice from SPF facilities to the laboratory use the service elevator and cover cages
with a lab coat. Do not transport mice through public areas.
Record all mouse procedures in the Mouse Colony 3-ring binder. This information will eventually be
entered into the Mouse Colony database.
CO2 canisters must be securely fastened to a wall.
When using formaldehyde or paraformaldehyde, work in fume hood and place in a secure rack
where dissection will take place. Keep tubes capped unless adding tissue to tubes. Decant all
used formaldehyde/paraformaldehyde into a hazardous waste container in the fume hood.
Always weare gloves.
Breeding, weaning & genotyping
In general, one male and one female will be housed for breeding purposes. In some
cases, up to three females will be placed in a cage with one male mouse (harem
breeding). Females in harem cages will be monitored and placed in a separate
cage before their litters are born.
When a litter is born, the date of birth will be noted on the cage card and the Mouse
Colony 3-ring binder.
Pups will be tail-clipped (<4 mm) between 14 days of birth and weaning for genotyping.
At the same time, the pups will be ear-clipped for tracking purposes.
Monitoring:
Mice will be housed in low-profile SPF housing with a maximum of four males or five
females per cage. They will be monitored daily including weekends and holidays
for signs of tumor formation or distress None of the animals is subject to any
discomfort or pain beyond the natural stress involved in the mating process and
due to handling of the adults. Specific tumor endpoint criteria to be used include:
a) A tumor that causes an impediment resulting in labored movement or the inability to
move, or that causes an impediment to normal body functions of the animal.
b) A tumor burden that causes a significant loss of body condition (e.g., muscle mass,
skin elasticity), resulting in an emaciated animal.
c) There is skin necrosis and/or ulceration over the tumor.
d) The animal exhibits marked lethargy, is unresponsive to a mild stimulus, or is
anorexic.
e) Clinical signs indicate the primary tumor(s) has metastasized, e.g., seizures, swollen
abdomen,labored breathing.
f) A tumor whose mass is greater than 25% of the animalʼs mass.
g) A tumor in mice whose volume exceeds 1 cm3
Euthanasia:
Mice will be aged up to 2 years or until they become moribund, whichever comes first.
At 2 years or when moribund mice will be euthanized using a CO2 chamber
following the guidelines approved by Research Animal Resources. The technique
is described below.
Necropsy:
Place mouse on a necropsy board and secure with dissecting pins. Use scissors and
tweezers to open mouse and remove organs. Place organs in tubes filled with
formaldehyde or in cryovials which are snap frozen in liquid nitrogen. Dispose of
carcasses and tissues by placing in plastic bag and depositing in approved RAR
refrigerator in the SPF facility.
Hazard Identification and Risk of Exposure to the Hazards:
Sharps, especially needles, scalpels, and scissors. Never recap needles, but place directly
in Sharps container.
Liquid nitrogen, possible burns
Formaldehyde solutions (10% buffered formalin and 4% paraformaldehyde) are
considered hazardous chemicals. They are probable human carcinogens (IARC Group
2A), skin and pulmonary sensitizer, irritant, reproductive toxic, acutely toxic (by skin
contact and inhalation), and corrosive
Exposure Controls Specific to Above Risk of Exposure:
PPE - Lab coats, face shield, gloves, respiratory mask and sharps containers. Work in
laminar flow hoods
All sharps and glass waste will be disposed of in an approved hard plastic sharps
container (U Stores # CX40245, MS07407 or similar), No Cardboard sharps pouches.
When handling liquid nitrogen, use insulated gloves and appropriate dewars to transport.
Always keep the dewar covered.
Waste Generated and Disposal Methods:
Dispose of animal carcass and tissues by sealing it in a plastic bag and placing in coolers
in RAR SPF facilities. Padding and towels with tissue or blood will be disposed of in
a designated biohazard waste container.
Sharps containers will be sealed when ¾ full and placed in designated waste area.
Formaldehyde products should be placed in a sealed container and labelled as
biohazardous waste. Arrange with UM DEHS for pickup when bottle is ¾ full.
Spill Response Procedures:
If a chemical spill occurs notify people in the area. Cover spill with enough paper towels
to absorb all the liquid. Place paper towels in a biohazard waste bag for disposal.
If exposed to formaldehyde or paraformaldehyde immediately rinse with copious
amounts of water and seek medical attention at Boynton Health Services, or Fairview
Emergency room if after normal business hours.
If punctured or cut, rinse with water and wash with soap and seek medical attention at
Boynton Health Services, or Fairview Emergency room if after normal business
hours.
Accident Response Procedures:
If Incident Results in a Hazard Exposure ( i.e. face or eye splash, cut or puncture with
sharps, contact with non-intact skin):
• Encourage needle sticks and cuts to bleed, gently wash with soap and water for 5
minutes; flush splashes to the nose, mouth, or skin with water; and flush eyes at the
nearest eyewash station with clean water for 15 minutes.
• Call 911 or seek medical attention.
- For urgent care employees may go to HealthPartners Occupational and
Environmental Medicine (M/F day time or Urgent Care after hours), or UMMCFairview Hospital (24 hrs). You may seek medical attention at the closest available
medical facility or your own healthcare provider.
- Follow-up must be done by HealthPartners Occupational and Environmental
Medicine.
• Report the incident to your supervisor as soon as possible, fill out the appropriate
documentation.
- Employee First Report of Injury
- Supervisor Incident Investigation Report
• Send Incident Report Form to the IBC if exposure has occurred during work on an
IBC protocol.
• Report all biohazard exposures to the Office of Occupational Health and Safety (612626-5008) or uohs@umn.edu.
Note: It is important to fill out all of the appropriate documents to be eligible to collect
workers compensation should any complications from the hazardous exposure arise in
the future.
Notes:
References:
For further information view the UMN DEHS website containing Bio Basic Fact Sheets
at http://www.dehs.umn.edu/bio_basicfacts.htm.
For general information on Biosafety, access the Biosafety in Microbiological and
Biomedical Laboratories (BMBL) 5th Edition from the CDC at BMBL
http://www.cdc.gov/biosafety/publications/bmbl5/index.htm
For Material Safety Data Sheets access the Public Health agency of Canada website
MSDS http://www.phac-aspc.gc.ca/lab-bio/res/psds-ftss/index-eng.php.