Policy for Performing Survival Surgery on Vertebrate Animals at Indiana University
All survival surgery in vertebrate animals must be performed using aseptic procedures,
including surgical gloves, masks, sterile instruments and aseptic techniques. Non-rodent
mammalian survival surgery must be performed in a dedicated operating room. Survival
surgery on rodents does not require a special facility but should be performed using sterile
instruments, surgical gloves and aseptic procedures to prevent clinical infections.
Guidelines for Aseptic Surgery in Rodents
The following guidelines for performing aseptic surgery on rodents were developed by the
IUPUI Animal Care and Use Subcommittee. These guidelines are intended to provide those
persons performing survival surgical procedures on rodents with sufficient information so
that procedures done in their areas are in compliance with the IU Survival Surgery Policy.
A. Pre-operative preparation
Rodents should be in optimal health prior to performing surgery. The veterinary staff of the
facility should be contacted anytime rodents appear ill, and surgery should not be
performed until the health status of animals has been determined. Recently shipped animals
should be given a period of adaptation of 3-7 days before surgery is performed in order to
allow them to become familiar with their new surroundings and to allow them to become
familiar with new food and sources of water. If animals will be placed into a different
environment following surgery, it is advisable to adapt them prior to performing surgery
(ie., group housing to single housing, conventional cage to metabolic cage).
Pre-surgical fasting is not generally required for rodents. However, it may be desirable to
withhold feed if surgery is to be performed on the gastrointestinal tract in order to reduce
the volume of intestinal contents.
B. Anesthesia
Appropriate anesthesia should be induced and maintained during the surgical period. An
adequate depth of anesthesia is indicated when the animal:
(a) is breathing regularly,
(b) has pink ears and mucous membranes,
(c) will not withdraw its foot when the toes are pinched, and
(d) will not blink when the eye or eyelid is touched. The veterinary staff should be
consulted for advice in selection of appropriate anesthetic agents, routes of
administration and dosages.
Hypothermia is a major complication of anesthesia in rodents, and where required, it should
be prevented by providing supplemental heat. Placing a circulating water heating pad under
the rodent at the time of surgery is ideal, but plastic bottles filled with warm water or
suspending a 75-watt bulb approximately 2 feet above the animal can also be used.
Extreme care must be used when placing unconscious animals under a light source, since
severe thermal burns can be produced if animals are not closely monitored until they have
regained mobility.
C. Surgical procedures
Surgical facility:
Areas where rodent surgeries are performed must be adequately sanitized. In most cases,
rodent surgeries are performed on a table or portion of a lab bench that has been
appropriately sanitized and is not used for any other purpose during the time of surgery.
Preparation of the incision site:
Hair should be removed from the incision site and the skin should be aseptically prepared
prior to surgery. For larger rodents, hair can be removed by clipping with electric clippers
using a #40 blade. For smaller rodents, hair can be plucked from the incision site of
anesthetized animals. The incision site should be scrubbed free of debris using a standard
surgical skin cleanser. The use of isopropyl alcohol alone is not a suitable means of
preparing skin for aseptic surgery. Care must be taken not to wet large areas of the
rodent's body when prepping the incision site--this will predispose the animal tohypothermia. For small rodents, cotton-tipped applicator sticks can be used to cleanse the
incision site. Sterile gauze sponges can be used for skin preparation in larger rodents.
When there is extensive exposure of tissues (laparotomy, thoracotomy), the surgical site
should be draped after it has been prepped. Drapes can be made from impervious materials
that can be sterilized; plastic sheets, plastic-backed paper, double layered cloth, aluminum
foil. Sheets of clear plastic make excellent drapes because the animal can be visualized
through the drape.
Surgical instruments:
The surgical instruments should be matched to the size of the rodent and the procedure in
order to minimize surgical trauma. Surgical procedures in small rodents require delicate
instruments such as those designed for micro or ophthalmic surgery.
All instruments, sutures, catheters, etc. that will have contact with the surgical site must be
sterile. Suitable methods for preparing surgical materials include the following:
a. Steam autoclaving--the most common means of sterilizing surgical equipment (items
are exposed to moist heat at 27ºF for 15-30 minutes)
b. Gas sterilization (ethylene oxide)--used to sterilize heat sensitive materials.
c. Liquid chemical disinfectant (ABQ, novalsan, zephiran, povidone iodine solutions)-when materials are disinfected by immersion in chemical solutions, they must be
accurately mixed and used according to the manufacturer's instructions. Immersed
materials must be rinsed with sterile saline prior to contacting tissues of live animals.
Failure to rinse caustic chemicals from instruments has produced severe chemical
burns in rodents.
Surgeon preparation:
Anyone touching the sterile surgical equipment or the operative site should wear sterile
gloves. Once gloved, care should be taken to touch only the sterile operative field and
equipment. In addition to sterile gloves, caps and masks must be worn, and the arms of the
surgeon must be covered (clean lab coat or surgical gown).
Advice for "Multiple Run" Procedures:
"Multiple run" refers to the same procedure being performed on a group of rodents
sequentially using the same surgical instruments. One way to minimize transfer of skin
bacteria to deeper tissues and between animals is to separate the instruments by function
when the instrument tray is prepared. For example, a pair of scissors and forceps are
assigned to skin incisions. A second scissors and forceps are assigned to subcutaneous and
abdominal wall incisions. Additional instruments are used to manipulate abdominal organs.
Blood and tissue debris are removed from instrument tips by rinsing them with sterile saline
between animals. The pack should be re-sterilized after it has been used on 4-5 rodents.
D. Postoperative recovery
Anesthesia recovery:
Most rodents recover rapidly and uneventfully from most surgeries. Animals should be kept
comfortable and warm, and they should be observed at frequent intervals (every 15-30
minutes) until mobility has been regained. Anesthetized animals should be positioned with
their heads and necks extended in order to maintain a patent airway. If there were
significant fluid losses during surgery, or the duration of the surgical procedure was long,
administration of warmed sterile saline or lactated ringer's solution (1 ml/100 g body
weight/anesthesia hour) by subcutaneous injection is recommended. Systemic analgesics
should be administered to rodents that have undergone orthopedic or invasive procedures.
The facility veterinary staff can be consulted for appropriate analgesic drugs and dosages.
Clinical recovery:
Animals should be examined daily until incisions are healed and sutures/wound clips have
been removed. Sutures are usually removed approximately 6-10 days following surgery.
Care should be taken to ensure proper food and water intake, to provide analgesic drugs for
pain relief, and to clean surgical sites to ensure proper wound healing. During this period, it
is the investigator's responsibility to check their animals each day, including weekends and
holidays. Any clinical problems must be promptly reported to the veterinary staff.
It is best to keep post-surgical patients separated from non-operated animals until the
incisions are healed because non-operated rodents may cannibalize the incision of the
recovering animal.
E. Recordkeeping requirements
Records of surgical procedures performed on rodents must be maintained. These records
should include: 1) a description of - the surgical procedure performed; 2) the anesthetics
used (including dosages and routes of administration); 3) monitoring procedures that were
done during surgery and in the postoperative recovery period (observations must be
recorded, at least daily, from the date surgery was completed until the date the incision has
healed); and 4) a description of any adverse anesthetic reactions or complications that were
encountered. Groups of rodents undergoing surgery on the same day can all be kept on a
single record. These records must be accessible to the Animal Care and Use Committee
during their semi-annual inspections and to the veterinary staff upon their request.
reviewed & approved by IU IACUC in August, 1993
drafted by C.M. Vogelweid