Notification from ACC Coordinator – SOP Updates

*** Important Notice *** SOP Updates for U of T Animal Research Community  9/14/2021

Dear U of T animal user community, 

Several SOPs have recently been updated and the notable changes are summarized below. 

  • Housing Mice
  • SOP: 5.11.0 Mouse & Rat Husbandry Procedures
  • Consult SOP for more details of allowances for each cage type at each facility. 
  • Notable Change: All mice are to be weaned/housed at a maximum of4 mice per cage to meet CCAC requirements for minimum floor space. This is new for some U of T animal facilities that previously housed up to 5 mice per cage. 
  • Deadline for Implementation: end of 2021 
  • Nesting Material
  • SOP: 5.11.0 Mouse & Rat Husbandry Procedures
  • Notable Change: All mouse and rat housing cages are to include nesting material.
  • Deadline for Implementation: immediately 


  • Secondary Method of Euthanasia
  • SOP: 12.2.0 Rodent Euthanasia (CO2, Chemical, & Physical)
  • Notable Change: All euthanized animals are to undergo an approved secondary method of euthanasia(unless a physical method was used as the primary method) before they are placed in the freezer. 
  • For mice, approved physical methods include cervical dislocation, thoracotomy, exsanguination (e.g., cardiac perfusion), or decapitation.
  • For rats, approved physical methods include thoracotomy, exsanguination (e.g., cardiac perfusion), or decapitation. Cervical dislocationis no longer an acceptable secondary method for rats.  
  • Deadline for Implementation: immediately


  • Euthanasia of Pregnant Females and of Neonatal Mice <10 days
  • SOP: 12.2.0 Rodent Euthanasia (CO2, Chemical, & Physical)
  • Notable Change: If females are pregnant with fetuses that are > 14 days gestation, following euthanasia of the female, you must decapitate all fetuses
  • Reminder that decapitation of neonatal mice <10 days is also required as they are resistant to CO2/iso.
  • Deadline for Implementation: immediately


  • Surgery 
  • SOP: 10.3.0 Sterile Techniques, Intra-Operative & Post-Operative Care
  • Notable Changes: 
  • Skin disinfectant– Chlorhexidine (2%) is to replace the use of iodine as skin disinfectant for surgical preparation by the end of the year. 
  • Suture material – Silk sutures are no longer acceptable. Instead use the following non-absorbable options (e.g., polypropylene, nylon) or long-acting absorbable sutures (e.g., Vicryl, PDS, polysorb). 
  • Heat source for surgeryElectrical pharmaceutical heating pads are no longer acceptable for operative or post-operative heat support as they can cause burns. Instead, use a circulating hot water/infra-red blanket, warmed oat bag, hot water bottle, heated stage, as appropriate. 
  • Deadline for Implementation: end of 2021

Access to the full SOPs can be found here.

If you have any questions or concerns, please forward them to



David Hanwell (he/him)

University Veterinarian and Director, Animal Ethics and Compliance

Research Oversight and Compliance Office (ROCO)

Division of the Vice-President, Research & Innovation | (647) 700-8692

General inquiries: