Guidelines for Survival Surgical Procedures in Rodents
Policy No: 104.06
Revision No: 4
Effective Date: October 22, 2013 (revised 02/25/14)
Category: Research Guidelines
------------------------------------------------------------------------------------------------------------------------------ASEPTIC TECHNIQUES FOR SURVIVAL SURGICAL PROCEDURES IN RODENTS
These guidelines apply to all surgical procedures performed on rodents at Thomas Jefferson
University in which the animals are expected to recover from anesthesia. Prior to performing
any survival surgery techniques on rodents, an approved Animal Use Protocol must be in place
with appropriately trained personnel and procedures available. Any exceptions to this policy
must be approved by the Institutional Animal Use and Care Committee (IACUC).
The following definitions should be considered in determining if the procedures you are
employing meet the requirements:
Survival Procedure
One in which an animal awakes from the anesthetic, even if for a short time.
Major Procedure
As a general guideline, major survival surgery (e.g., laparotomy, thoracotomy, joint
replacement, and limb amputation) penetrates and exposes a body cavity, produces
substantial impairment of physical or physiologic functions, or involves extensive tissue
dissection or transection (Guide, 2011).
Minor Procedure
Minor survival surgery does not expose a body cavity and causes little or no physical
impairment; this category includes wound suturing, peripheral vessel cannulation,
percutaneous biopsy, routine agricultural animal procedures such as castration, and
most procedures routinely done on an “outpatient” basis in veterinary clinical practice
(Guide, 2011).
Surgical Laboratory for Rodents
Dedicated surgical facilities are not required for rodent surgery. Although the
investigator's laboratory is suitable, the site upon which surgery is going to take place
should be free of all ancillary equipment and should provide a clean and clear work area
in which the investigator will perform the procedures.
PROCEDURES
1. Surgery should be conducted in a disinfected, uncluttered area that promotes asepsis
during surgery.
Prior to and after the completion of all surgical procedures, all organic debris should be
removed and cleaned from work surfaces. Refer to Table 1 for recommended disinfectants.
2. All surgical instruments must be cleaned and sterilized prior to use.
All surgical supplies and equipment must be cleaned prior to sterilization in order to remove
any organic material that may interfere with the sterilization process. Surgical instruments may
be cleaned in an ultrasonic cleaner or by hand, using a stiff bristle brush and a moderately
alkaline, low sudsing detergent. Deionized or distilled water is preferred for cleaning.
All surgical instruments/implantable devices, and equipment that will contact the surgical site
or are implanted in the animal are to be sterilized. Devices for sterilization can include
autoclaves, gas sterilizers, bead sterilizers and chemicals. It is not recommended to use bead
sterilization as the initial sterilization procedure. Sterilization must be verified. Methods of
sterilization for autoclaves and bead sterilizers can be confirmed by use of spore vials, heat
strips or chemical strips. Chemical sterilization requires strict adherence to time/concentration
standards recommended by the manufacturer. See Table 2 for guidance.
3. Procedure for multiple survival surgeries.
If more than one surgery is planned, the same set of previously sterilized surgical instruments
can be used for subsequent surgeries. Ideally the surgeon should have at least two sets of
sterile instruments so that the surgeon may continue to work while the used instruments are
being disinfected. The instruments must first be cleaned of organic material and then resterilized. A bead sterilizer is ideal because sterilization time is approximately 10 seconds
followed by a short cooling time (usually 30 seconds) before use. Alcohol must not be used for
sterilization of instruments between animals. It is neither a sterilant nor a high level disinfectant
as it is inactive against bacterial spores, many viruses, and does not penetrate surfaces well.
4. The surgical site must be aseptically prepared.
Remove hair or fur from an area approximately 200% larger than the area of the incision.
Surgical preparation of the skin: a number of agents are available for this purpose. We
recommend the use of either povidoneiodine scrub (Betadine® Scrub) or chlorhexidine scrub
(Nolvasan®). Both of these agents have good bactericidal activity and contain a detergent.
Using 3x3 gauze squares (or the equivalent), the area should be scrubbed beginning at the
center of the incision site working out to the perimeter. After reaching the perimeter, a new
gauze square should be selected and the process repeated. After completing the above
preparation, the area should be washed with gauze 3x3's soaked in 70% isopropyl alcohol or
70% ethanol. Alcohol, by itself, is not an adequate skin disinfectant. The surgical site may be
outlined by a sterile drape.
5. The surgeon must be adequately prepared prior to the initiation of surgery.
Although the requirements for preparation of the surgeon in rodent surgery are less rigorous
than what is required for higher mammals, proper preparation is still necessary. Either a clean
laboratory coat or a surgical scrub shirt must be worn by the surgeon and any assistant(s). In
addition, a surgical mask and head cover should be worn. After preparing the surgical site, the
surgeon should wash his/her hands with a disinfectant and then don the recommended sterile
surgical gloves. Refer to Table 3 for suggested disinfectants.
6. Appropriate suture material should be used to ensure adequate closure.
Selection and care of appropriate suture materials is imperative for successful wound closure.
Sutures are either absorbable or non-absorbable. Wound clips may be used for skin closure in
rodents. It is imperative that suture materials are sterile, since they are a foreign material and
provide a substrate where bacteria may proliferate. Table 4 provides information on various
suture materials. The smallest gauge that will perform adequately should be used. In most
cases, 3-0 or smaller is used in rodent surgeries. Cutting needles have the ability to cut through
dense tissues, such as skin. Taper needles should be used to suture tissues that tear easily, such
as peritoneum or abdominal organs.
7. Postoperative care must be provided.
Postoperative care programs should be considered and designed before commencing
any experimental procedures. A number of factors (e.g., type of surgery performed,
type and amount of anesthetic used) will modify the nature, duration, and intensity of
the postoperative care required by the animal patient.
The following minimal essential components should be routinely incorporated into
postoperative management of animals:
1. The animal should be kept warm by the use of heating pads, blankets or lamps, and, if animal
size permits, body temperature should be monitored and recorded until it returns to normal.
2. Hydration should be assessed on a regular basis and fluid replacement administered at a
volume of 40-60 ml/day/kg body weight for animals weighing over 1 kg. A larger volume of
fluids (100 ml/kg/day) is required for animals weighing less than 1 kg. Fluids need to be
administered twice daily to animals which are not eating and drinking postoperatively. In
laboratory rodents, fluids may be given subcutaneously or intraperitoneally. Lactated ringers
solution or equivalent should be utilized. Hydrogel can be provided to rodents if needed. This
can be obtained from the laboratory animal resource staff.
3. Skin sutures or wound clips should be removed 7 to 10 days postoperatively.
4. Analgesics listed in your Animal Use Protocol must be provided according to dose, route, and
duration listed in the protocol. Analgesics should be utilized in animals which demonstrate pain
related behavior (i.e., guarding of the incision, reluctance to move, anorexia, absence of normal
behavior patterns).
5. Appropriate surgical and postoperative care records must be kept. Individual records may or
may not be required for rodent surgeries. In some cases, group records will suffice. Consult the
veterinarians for clarification on this issue.
TABLE 1: RECOMMENDED HARD SURFACE DISINFECTANTS
(Always follow manufacturer's instructions for dilution and expiration periods. The use of
common brand names as examples does not indicate a product endorsement.)
AGENT
EXAMPLES
COMMENTS
Alcohols
70% ethyl alcohol, 85%
Contact time required is 15 minutes.
isopropyl alcohol
Contaminated surfaces take longer to
disinfect. Remove gross contamination
before using. Inexpensive.
Quaternary Ammonium Roccal®, Quatricide®
Rapidly inactivated by organic matter.
Compounds may support growth of gram
negative bacteria.
Chlorine
Sodium hypochlorite
Corrosive. Presence of organic matter
(Clorox ® 10% solution)
reduces activity. Chlorine dioxide must
Chlorine dioxide (Clidox®, be fresh; kills vegetative organisms
Alcide®, MB10®)
within 3 minutes of contact.
Glutaraldehydes
Glutaraldehydes (Cidex®, Rapidly disinfects surfaces.
Cetylcide®, Cide Wipes®)
Phenalix
Lysol®, TBQ®
Less affected by organic material than
other disinfectants.
Chlorhexidine
Nolvasan® , Hibiclens®
Presence of blood does not interfere
with activity. Rapidly bactericidal and
persistent. Effective against many
viruses.
TABLE 2: RECOMMENDED INSTRUMENT STERILANTS
(Always follow manufacturer's instructions for dilution and expiration periods. The use of
common brand names as examples does not indicate a product endorsement.)
AGENTS
EXAMPLES
COMMENTS
Steam
Autoclave
Effectiveness dependent upon
Sterilization
temperature, pressure and time (e.g., 121oC for 15
(wet heat)
min. vs 131oC for 3 min).
Dry Heat
Hot Bead Sterilizer, Fast. Instruments must be cooled before contacting
Dry Chamber
tissue. Only tips of instruments are sterilized with hot
beads.
Gas Sterilization Ethyline Oxide
Requires 30% or greater relative humidity for
effectiveness against spores. Gas is irritating to tissue;
all materials require safe airing time.
Chlorine
Chlorine Dioxide
6 hours required for sterilization. Corrosive to
Glutaraldehydes Glutaraldehyde
(Cidex®, Cetylcide®,
Metricide®)
Hydrogen
Actril®, SporKlenz ®
peroxide/acetic
acid
instruments. Instruments must be rinsed with sterile
saline or sterile water before use.
10 hours required for sterilization. Corrosive and
irritating. Instruments must be rinsed with sterile
saline or sterile water before use.
6 hours required for sterilization. Corrosive and
irritating. Instruments must be rinsed with sterile
saline or sterile water before use.
TABLE 3: SKIN DISINFECTANTS
(Always follow manufacturer's instructions for dilution and expiration periods. The use of
common brand names as examples does not indicate a product endorsement.)
AGENTS
EXAMPLES
COMMENTS
Iodophores
Betadine®,
Reduced activity in presence of organic matter. Wide
Prepodyne®,
range of microbicidal action. Works best in pH 6-7.
Wescodyne®
Cholorhexidine Nolvasan®, Hibiclens® Presence of blood does not interfere with activity.
Rapidly bactericidal and persistent. Effective against
many viruses. Excellent for use on skin.
TABLE 4: WOUND CLOSURE SELECTION
(Always follow manufacturer's instructions for expiration periods. The use of common brand
names as examples does not indicate a product endorsement.)
MATERIAL
CHARACTERISTICS AND FREQUENT USES
Polyglactin 910 (Vicryl®),
Absorbable; 60 to 90 days. Ligate or suture tissues where
Polyglycolic acid (Dexon®)
an absorbable suture is desirable.
Polydiaxanone (PDS®) or,
Absorbable; 6 months. Ligate or suture tissues especially
Polyglyconate (Maxon®)
where an absorbable suture and extended wound
support is desirable
Polypropylene (Prolene®)
Non-absorbable. Inert.
Nylon (Ethilon®)
Non-absorbable. Inert. General closure.
Silk
Non-absorbable. (Caution: Tissue reactive and may wick
microorganisms into the wound). Excellent handling.
Preferred for cardiovascular procedures.
Chromic gut
Absorbable. Versatile material.
Stainless Steel Wound Clips, Staples Non-absorbable. Requires instrument for removal.
Cyanoacrylate (Vetbond®,
Skin glue. For non-tension bearing wounds.
Nexaband®)
REFERENCES:
Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, MA.
NIH Guidelines for Survival Rodent Surgery
National Research Council of the National Academies. (2011). Guide for the care and use of
laboratory animals (8th ed.). Washington, DC: National Academies Press.