Aseptic Surgical Techniques

The goal of aseptic technique is to reduce the possibility of microbial contamination to the lowest practical level. No single technique, practice, germicide, or piece of equipment will achieve this objective. Rather, proper aseptic technique is dependent on numerous practices that require input and cooperation of all personnel within the operating area.
Components of successful aseptic technique include:

  • Preparation of the animal
  • Preparation of the surgeon
  • Sterilization of instruments and supplies
  • Antibiotic usage

Preparation of the Animal

  • After the animal has been anesthetized, the eyes should be lubricated with a sterile ophthalmic ointment to prevent corneal drying.
  • The surgical area prepared should be approximately twice that needed for the incision, in the event a larger incision than planned may be required.
  • Hair should be removed from the surgical site, preferably with electric clippers (# 40 blade) or depilatory rather than a razor.
  • The skin should then be cleaned and disinfected with alcohol, followed by a chlorhexidine or povidone iodine-based disinfectant. The site should be scrubbed by starting at the center of the site and working outward in a circular pattern. Typically, three scrubs with a disinfectant is adequate, followed by an alcohol rinse.
  • A sterile surgical drape should be used whenever possible to isolate the disinfected area from surrounding tissue and hair. To be effective, a drape should adhere tightly to the skin and be impermeable to moisture.

Preparation of the Surgical Team

  • The surgeon must scrub the hands and forearms with a disinfectant soap for a minimum of three (3) minutes and then dry them with a sterile towel prior to survival surgery in all species.
  • Sterile gloves must be used for all procedures. Gloves must be replaced or sterilized with a cold sterilant between rodents if surgeries are being performed on multiple animals.   A new pair of sterile gloves must be worn for each large animal surgery.
  • The surgeon must wear a clean lab coat, scrubs, or smock while performing surgery on rodents; a cap, face mask, shoe covers and sterile gown must be worn for all survival surgeries in non-rodent species.
  • A surgical mask and a cap or hair net are also recommended to reduce the risk of gross contamination of the surgical site

Sterilization of Instruments and Supplies

All instruments and supplies that come in contact with the surgical site must be sterile. A number of options are available to sterilize surgical equipment and supplies:

  • Autoclave - Relies on pressurized steam, is extremely reliable, and cost effective. However, instruments must be durable (e.g., stainless steel) and the process is relatively slow, from 15 to 60 minutes. Instruments are typically wrapped or sealed in packs that are opened as needed on the day of surgery.
  • Ethylene oxide - A gaseous sterilant that requires specialized containment equipment. This is a good sterilization method for supplies that cannot tolerate high heat such as plastics and catheters. It is more costly than autoclaving and typically is performed overnight.
  • Cold sterilant solutions (hypochlorite, glutaraldehyde, etc.) - Generally, cold sterilants must have prolonged contact time (15 - 60 minutes) to sterilize surgical equipment. In addition, the instruments must be rinsed completely with a sterile solution like saline to prevent tissue irritation. Note: Alcohol is not a sterilant.
  • Hot bead sterilizer - This device is a small tabletop unit, approximately 6 x 6 x 8 inches. The appliance heats a small container of Pyrex beads to approximately 250 C and can sterilize the tips of metal surgical instruments in 10-20 seconds. It is very useful for sterilizing instruments between rodents when performing multiple surgeries.
  • Pre-sterilized items- Many instruments and supplies can be purchased in sterilized packaging. Such items must be used prior to the label expiration date.


  • In general, antibiotics should not be needed for short procedures if proper aseptic technique is followed throughout the surgery and the surgeon is well trained or experienced.
  • If used, antibiotics should be administered before the start of surgery so adequate tissue levels are present throughout the surgery.
  • An appropriate antibiotic should be selected based on species, spectrum of activity, dosing frequency and probable organism and sensitivity. Please contact Veterinary Services for assistance in selecting an appropriate antibiotic.
  • Antibiotics should not be used in place of surgical asepsis and good tissue handling techniques.

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