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Aseptic Technique Policy Statement

Aseptic technique comprises the processes and procedures that are used to prevent contamination of the animal’s tissues during surgery, which could lead to infection.


Contamination and infection are to be avoided, as they lead to pain and suffering in the animal, as well as having the potential to increase variability in the surgical model, thus reducing data quality. Aseptic technique can therefore be regarded as a controllable variable in surgical studies.


Presence of infection may not always be obvious to the external observer, as low-grade and chronic states occur, but which still have biochemical, immunological and physiological effects on the animal. Infection is likely to compromise the integrity of implants, leading to loss of function, or loss of the animal from the study. Additionally, therapies needed to treat the infection may present confounds for study data, increasing variability and requiring more animals to be used.


EALAS’s position is that good experimental surgical practice requires that proper aseptic technique must always be applied whenever recovery surgery is carried out, on animals of all species.


Achieving aseptic technique in surgery requires attention to the following four basic areas:


  1. Sterilisation of all instruments, implanted materials and consumables, using a validated method, such as autoclaving.

  2. Preparation and use of a dedicated surgical area that is de-cluttered and disinfected prior to use. Sterile drapes are used to allow placement of instruments and consumables.

  3. Preparation of the surgeon, including suitable hand scrub, and donning sterile gown and sterile gloves. Once wearing sterile gloves, the surgeon must not touch non-sterile items. Other PPE may be required, including face mask and hat.

  4. Preparation of the animal, including clipping of hair around the surgical site, skin preparation using aqueous scrub and use of a sterile drape to separate the incision site from the remainder of the animal.


It is very challenging to implement and maintain aseptic technique when the surgeon is operating alone, so it is strongly recommended that an assistant is present during the procedure, in order to pass items to the surgeon, and to monitor recovering animals.



Surgery on several animals (“Batch surgery”):


Preparation should be the same as for a single surgical procedure, in that all instruments, consumables and equipment must be sterilised using a validated method, and the surgeon and animal(s) should be prepared as above. The surgeon and team should be realistic about the number of animals that can be operated on in a single session, while still taking account of their good welfare and recovery.


Due to the risk of contamination, all equipment must be cleaned and sterilised between each animal; similarly, the same consumables should not be used on sequential animals. Ways of working that manage this process may include pre-sterilisation of a number of surgical kits, recycling used instruments through a rapid autoclave cycle, or use of disposable instruments, which are cheap and readily available. It is also possible to use a ‘hot bead steriliser’, with the caveat that the instrument tips must be cleaned before insertion, adequate dwell times observed and the instrument allowed to cool before re-use. The surgeon should be aware that only the instrument tips are sterilised by this method, so if the handles become contaminated, the instrument must be replaced.


Non-recovery surgery:


It is recommended that the principles of aseptic technique are applied during non-recovery procedures, unless it is certain that the data outputs will not be affected by risk of infection. The requirement to use aseptic practices may be more relevant where the procedure is invasive (involving a body cavity), or of longer duration (more than 1 hour).


For more information, see:


LASA 2017 Guiding Principles for Preparing for and Undertaking Aseptic Surgery. A report by the LASA Education, Training and Ethics section. (E Lilley and M. Berdoy eds.).


National Research Council 2011. Guide for the Care and Use of Laboratory Animals: Eighth Edition. Washington, DC: The National Academies Press.

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