Washington State University

Institutional Animal Care and Use Committee

Guidelines for Survival Rodent Surgery

Post-operative infections in rodents can and do occur. Such infections, which may not be apparent on casual observation, cause distress to and can endanger the animal, as well as endanger the results of the study. Both the Animal Welfare Act (AWA) and the NIH Guide for the Care and Use of Laboratory Animals ( The Guide ) contain standards for surgical procedures and surgical facilities. The Guide states that "survival surgery on rodents does not require a special facility, but should be performed using sterile instruments, surgical gloves, and aseptic procedures.

A rodent surgical area can be a room or portion of a room that is easily sanitized and not used for any other purpose during the time of surgery." If assistance and training is required in developing appropriate surgical and aseptic techniques, contact the Office of the Campus Veterinarian (OCV) at 335-6246.

Pre-Operative:

1. Surgery must be conducted in a disinfected (see Table 1), uncluttered work area. Traffic in surgery area should be limited during surgical procedure. Surgery area should be separate from location used for animal anesthesia, hair removal and surgical prep.
2. Any parenteral solutions (e.g. anesthetics, pharmacological agents, biological substances) to be used in the surgical procedure must be prepared and maintained in a sterile manner.
3. Appropriate preparation of the animal, including removal of the hair and a disinfectant scrub of the skin at the surgical site. Appropriate skin disinfectants include Iodophors (Betadine´, Prepodyne´) and Chlorohexidine (Nolvasan´, Hibiclens´). The scrub solution should be removed with a 70% alcohol wipe. The scrub - wipe routine should be repeated three times and then followed with the disinfectant solution painted on the site. Minimize soaking the body of the rodent as this could lead to hypothermia and possible death.
4. It is strongly recommended that a small amount of plain, sterile ophthalmic ointment be instilled in each eye of the anesthetized animal prior to surgery to prevent corneal drying. This is particularly important for lengthy surgical procedures.
5. Surgeons should wash hands with an antiseptic surgical scrub preparation prior to surgery. Sterile gloves and a surgical mask must be worn by the surgeon and any assistants working in the immediate surgical field. Surgeon and assistants should wear clean laboratory garments.

Operative:

1. The animal must be maintained in a surgical plane of anesthesia throughout the procedure. Monitor and maintain animal's vital signs through out procedure.
2. For lengthy surgical procedures (30+ minutes), supplemental heat should be provided to the animal to prevent hypothermia. Items used for supplemental heat should not set higher than 29-32°C (85-90°F) to prevent thermal-induced necrosis of the skin. The use of commercial electrical heating pads is discouraged as thermal burns have been reported when using these devices. Using a water-circulating water blanket is recommended to reduce the risk of injury to the animal.
3. Begin surgery with sterile instruments, supplies, implants, and wound closure material. See WSU - IACUC Guidelines for Sterilization of Instruments and Surgical Supplies for Aseptic Surgical Procedures . All instruments and materials used in the surgical procedure must be handled aseptically.
4. Similar surgical procedures may be performed on multiple rodents (limit 4-5 animals) during a single session using one sterile surgical pack, providing care is taken to avoid contamination . It is recommended the instruments be soaked in an appropriate disinfectant (see Table 2) and rinsed with sterile water or saline between animals. An alternative method of sterilizing instrument tips between surgeries is the use of a glass bead sterilizer (dry heat). If appropriate precautions are taken to minimize contamination of surgical gloves, it is adequate to rinse the gloves with a disinfectant (see Table 2) between animals. If surgical gloves become contaminated by handling/touching non-sterile items, they must be replaced immediately with sterile gloves before the surgical procedure continues. Surgeries which could be potentially "dirty" (e.g. within the gastrointestinal tract, or in the presence of infected wounds) should only be conducted using a single set of sterile instruments.
5. Draping the surgical site with sterile drapes to avoid contamination of the incision, instruments, supplies is preferred. As a minimum, sterile folded gauze sponges or a small piece of drape should be utilized to prevent contamination of the instrument tips and exteriorized tissue.
6. Close surgical wounds using appropriate techniques and materials (see Table 3). Closure of the skin with non-capillary, non-absorbable material is essential to reduce the risk of post-operative infections.

Post- Operative:

1. Move the animal to a warm, dry area and monitor vital signs during recovery. Return the animal to routine housing only after it has fully recovered from anesthesia.
2. Provide analgesics as appropriate. Questions regarding the appropriate analgesics and dosages should be directed to the OCV staff at 335-6246.
3. Generally, remove skin closures 7 to 10 days post-operatively.
4. Maintain a surgical record (e.g. annotate cage card with procedure and date).
5. In the event of postoperative complications (e.g. infection, lengthy recovery, death), contact the OCV staff as soon as possible.

References:

1. Cunliff-Beamer, T.L., Applying Principles of Aseptic Surgery to Rodents , AWIC Newsletter (1993) Vol. 4 No. 2; 3-6 ( http://www.nal.usda.gov/awic/newsletters/v4n2/4n2.htm )
2. Office of Animal Care and Use, NIH Intramural Research Program, Guidelines for Survival Rodent Surgery , ( http://oacu.od.nih.gov/ARAC/surguide.htm )

Table 1. Recommended Hard Surface Disinfectants:    e.g. table tops, surgery tables, auxiliary equipment
 

* The use of common brand names as examples does not indicate a product endorsement.
 

Table 2. Recommended Instrument Disinfectants - Only for Use Between Multiple Rodent Surgeries:

(Surgical session must begin with sterile instruments. Instruments must be rinsed thoroughly with sterile water/saline to remove chemical disinfectants prior to used. No more than 4-5 animals per session/sterile pack)
 

* The use of common brand names as examples does not indicate a product endorsement.
 

Table 3. Recommended Suture Selection:

• Suture gauge selection: Use the smallest gauge material that will perform adequately.

• Cutting and Reverse cutting needles: Provides edge that will cut through dense, difficult to penetrate tissue (e.g. skin)

• Non-cutting, taper point or round needles: Have no edges to cut through tissue; Used primarily for suturing easily  torn tissue (e.g. peritoneum or intestines)

* The use of common brand names as examples does not indicate a product endorsement.