Surgery: Aseptic
BU IACUC Revised January 2014, Revised May 2019, Revised 1 August 2023
As stated in the Guide for the Care and Use of Laboratory Animals (NAS, 2011), which our assurance with the federal government requires us to follow, both major and minor surgical procedures on laboratory animals require aseptic technique and instruments. Therefore, all survival surgeries performed on any vertebrate must employ aseptic technique. This means setting up and maintaining a sterile field and utilizing sterile instruments and technique throughout the surgery.
In addition, the Guide expects a dedicated area for all surgeries performed on vertebrate animals. A dedicated surgery suite, such as the one maintained by the Animal Science Center), must be used for larger species,). For rodents, birds and other smaller species, including aquatics, there should be a dedicated surgical area, such as defined bench space separated from other activities. Survival surgery performed at field sites may be exempt from these provisions but must still be performed using aseptic technique. Exceptions to these guidelines must be justified and approved by the IACUC.
Animal protocols must specify that all survival surgeries will be done using aseptic technique. Details of aseptic technique during each surgical procedure must be included in the protocol. If aseptic technique and instruments cannot be used, scientific justification must be provided in the protocol to be reviewed by the IACUC.
Aseptic technique includes preparation of the animal subject and the surgeon. Preparation of the animal includes removal of fur or feathers, if applicable, and scrubbing of the surgical site with appropriate disinfectant (e.g. chlorhexidine or povidone iodine alternating with 70% ethanol several times for mammalian species) prior to incision. Preparation of the surgeon includes appropriate garb: sterile gloves, surgical mask, hair bonnet, and either surgical gown or lab coat, depending on the species. Instruments must be sterilized prior to use. Autoclave and gas sterilization are appropriate to sterilize instruments before each surgical session. Glass bead sterilizers may be used between surgeries for up to five rodents in a single session. All implanted materials must also be sterile unless scientifically justified. Alcohol is not a sterilant. All surgeons must employ operative techniques to reduce likelihood of infection, including aseptic technique, minimizing time to complete the surgery, and ensuring competency with the procedure.
Surgeon Prep
Attire: clean lab coat or scrub top and remove all jewelry (rings, bracelets, watches) on the hands and wrists. Don a face (surgical) mask and hair bonnet or cap for all surgeries.
Gloving: Wash and scrub hands with a disinfectant soap, or surgical scrub brush, and dry with clean towels. Wear sterile gloves. Change gloves between animals or if the gloves become contaminated. Sterile latex surgical gloves may be purchased or nitrile exam gloves may be sterilized by autoclaving (LeMoine 2015).
Maintaining sterility: Anything touching the drape or the sterile field must also be sterile. Sterile gauze pads or sterile pieces of aluminum foil may be used to manipulate non-sterile objects.
Maintenance of Gas Anesthesia Apparatus
Annual inspection and maintenance of the isoflurane vaporizer by professional contractor or qualified personnel is required. This is managed by ASC. Some newer low flow machines (e.g. Somnoflo) may not require annual maintenance, but manufacturer literature that supports that should be available near the machine for inspections.
F/air (or equivalent) charcoal canisters are used to capture waste anesthetic gases. Canister saturation must be monitored by tracking and documenting time used or by increased weight to determine when a gas filter canister should be replaced. Make sure the bottom of the canister is not blocked or covered to allow unimpeded flow of air over the charcoal. An instructional video for use is provided here.
Environmental Health and Safety will determine personnel exposure to isoflurane as needed and advise users.
An “elephant trunk” anesthesia gas exhaust duct (also known as a snorkel) connected to the room exhaust air duct is strongly recommended over a charcoal canister.
Maintenance of Autoclaves Used to Sterilize Surgical Instruments
Autoclave performance should be monitored with each load by using temperature-sensitive tape designed for that purpose. In addition, autoclaves, including benchtop models, must be validated for performing sterilization by using biologic test strips designed for that purpose; biological validation should be performed at least annually and after any repairs. Logs of biological indicator cycles should be maintained. Biological indicators are available through ASC and may run in their incubators.
Guide for the Care and Use of Laboratory Animals (Eighth Edition, 2011) pp 115-120, 144-145
Animal Welfare Act 2.31 (d) (1) (ix)
Also see: Surgery: Rodent