Animal surgery and anesthesia at UiB

Prepare a protocol and a list of equipment that will be required before you start any surgical procedure.

Make sure all the required facilities and equipment have been booked.

Ensure an assistant is available.

Make sure equipment is prepared for use.

When using heat pads, monitor the temperature of both the animal and the heat pad, to ensure correct operation.

Check that your animals a healthy anb fit for surgery

Instruments must be handled safely - avoid unnecessary maneuvers

Instruments must be sterilized before they are used for aseptic surgery.

• Ideally, a separate set of sterilized instruments should be used for each animal.

For batch surgery for rodents, an acceptable compromise is to sterilize the instrument tips using a hot bead sterilizer.

Instruments first need to be cleaned using a sterile brush, in sterile water, to avoid becoming clogged with organic material.

Sterile water must be used (not saline water) for cleaning instruments before use of a hot-bead sterilizer.

Some brands of toothbrush can be autoclaved successfully, and included in the instrument pack.

The instrument tips are briefly placed into the hot-bead sterilizer, according to the manufacturer’s instructions.

Replace them on a sterile drape, ready for use on the next animal.

Briefly immersing instruments in alcohol is NOT an effective means of sterilization.

All other materials needed for the surgical procedure that will come into contact with the surgical site must be sterile, and must be used within their stated expiry dates.

It is often convenient to purchase items such as scalpel blades and sutures in sterile packs, which are opened when required.

Delicate materials, for example catheters, which could not withstand autoclaving can be purchased pre-sterilized, or sterilized using other methods, such as ethylene oxide.

Clip the fur from the surgical site after the animal has been anaesthetized.

• Use clippers (not razors) with clean sharp blade
• Remove the clipped fur with a vacuum cleaner.
• Perform this initial clipping in a separate area so that the operating area is not contaminated.

When clipping mice, particular care needs to be taken to avoid damaging the delicate skin.

Clean the skin using a suitable disinfectant, for example Chlorhexidine, either in alcohol or water – but avoid using too much disinfectant solution, as this can increase the risk of the animal becoming hypothermic.

Alcohol alone is not suitable for disinfection of the skin.

In both rats and mice, ointment should be applied to the eyes to prevent drying during anaesthesia (this is also true for animals undergoing imaging).

Good surgey begins prior to any incision being made

with consideration to both the equipment needed and the approach to be used

Good surgical techniques afects your outcome

Shedding from operational room personnell is the priary source of contamination in the operation room

Therefore:

• The surgeon should wear appropriate protective clothing to avoid contaminating the surgical site.
• Wearing a head cover and mask is strongly recommended, but the most important step is for the surgeon to perform effective disinfection of their hands, by “scrubbing up” and then putting on a sterile gown and sterile surgical gloves.
  • A gown i sused to decrease the spread of bacteria and other particles from the surgeons skin and clothes to the operation environment.
• The process of hand-washing aims to remove surface dirt and grease from your skin, and allow sufficient contact time with the disinfectant soap to kill or inhibit bacteria in the outer layer of the skin.
  • Remove rings/jewelry
• The only time a scrubbing brush should be used is to clean under your nails, the remainder of the process is just careful and repeated hand-washing.
• Total contact time varies with the disinfectant used – 5 minutes is recommended for Chlorhexidine and Povidone.

An assistant should be avialable to open the outer wrapping of instrument packs, sutures, scalpel blades and other material that will be needed during surgery.

The surgeon needs to take care, when unwrapping the pack to drop the corners of the drapes, so that the back of their hand does not touch the surface of the table.

• The surgeon drapes the animal, once again taking care not to touch any non-sterile surface.

Using drapes prevents sterilized items touching the animals’ fur, and becoming contaminated.

• When using a paper drape, a suitable-sized hole can be cut to access the surgical site. Avoid cutting along one of the pre-folded sections as this can prevent the drape conforming to the animal.

The sterile field can be extended by using an additional paper or cloth drape.

Drapes may need to be cut to size, or positioned carefully so that the position of the animal’s nose in the facemask can be monitored – alternatively a transparent drape can be used.

Ideally drapes should:

• Be resistant to penetration of bacteria and body fluids (Blood, flush waer)
• Should not tear with normal use
• Secured so it remain effectivelu in position during surgery
• Dot flammable

Several mask designs (such as the one used to anaesthetize the mouse) provide much more secure placement of the animal’s nose.

The position of the head can be fixed using tape, but care must be taken not to interfere with respiratory movements, or to fix the animal’s limbs in an abnormal position.

Aseptic techniques can be maintained throughout a series of procedures but use of an assistant becomes almost essential.

After completing the first procedure, the surgeon lifts and disposes of the sterile drape.

The assistant then moves the animal to a recovery area, or directly into a warm incubator.

The next animal to undergo surgery is then anaesthetized, clipped, positioned on the table and a skin preparation undertaken by the assistant.

Ideally the surgeon will use a new set of instruments, but it is acceptable to use a hot bead sterilizer to re-sterilize the tips of the instruments.

If a new set of instruments is to be used, the surgeon should re-glove before handling them.

This can be done without the need to re-gown.

The surgeon re-drapes the animal using a new sterile drape and carries out surgery.

Batch surgery means that several animal are anesthetized and operated in the same “batch”

On the animal welfare body meeting January 31 2018 we agreed on the following policy for batch surgery

• The maximum number of animals to be anesthetized at the same time is 3
  • This is to limit workload to what is possible to perform in a responsible way with regard to asepsis, anesthesia monitoring and animal welfare.
• There should be sterile instruments for each animal

Aseptic techniques can be maintained throughout a series of procedures but use of an assistant becomes almost essential.

1. After completing the first procedure, the surgeon lifts and disposes of the sterile drape.
2. The assistant then moves the animal to a recovery area, or directly into a warm incubator.
3. The next animal to undergo surgery is then anaesthetized, clipped, positioned on the table and a skin preparation undertaken by the assistant.
4. The surgeon re-drapes the animal using a new sterile drape and carries out surgery.

Careful tissue handling will reduce the riks of complications

Avoid extra strain and stress on tissues - apply sharp anatomic dissection of tissues - clean, perpendicular cuts, single sweeps

Use surgical intruments correctly - corect grip - correct manipulation

Appose tissues accurately with minimal tension and eliminate dead space not to disruppt blood supplying vessels

Control hemorrhage and preserve blood supply to tissues

All animals must be monitored until fully awake. If available- use an incubator (most animals are hypothermic to a greater or smaller extent after anesthesia)

Animals must not be left incapacitated until fully awake (must be protected from cages-mates), and should only be returned to their homecage once fully awake.

Animals that have undergone major invasive surgery (for example, but not limited to: intracranial or intra-abdominal surgery), sufficient post-operative pain relief must be provided. This usually requires 2-3 days of opiate treatment, but NSAID’s are also indicated.

All animals must be checked daily after surgery, and if indicated; several times a day. A note should be made in the book in the front room so that technicians are aware that the animals are seen to. The telephone number of the named surgeon must be available at all times.

The scoresheet should be used to evaluate the animals.

13 risk factors for surgery - how can you avoid these by applying best prcatices?

1. More than 10⁵ bacteria per gram tissue - maintaing aseptic conditions is crucial for the whole perio of surgery
2. Unclean and unnessary cuts thar are colonized by bacteria
3. Clipping fur other than immediately before surgery
4. The riks of surgical infection doubles approximately for every hour of surgery
5. 30% increased risk of wound infection for each additional hour of anesthesia
6. Shedding from operatimng room personnell
7. Underlyimng diseases
8. Age
9. Immuneuppression
10. Hypotension and Hypotermia
11. Body condition (malnutrition, obesity)
12. Blood loss
13. Suture material

Tips and tricks to refine surgical skills without use of animals

More videodemonstrations og and tips for surgery is available from NC3Rs here