Hair removal

The patient’s hair must be removed from the surgical site and surrounding area.

  • hair contains large numbers of microorganisms
  • hair prevents proper skin cleaning
  • hair causes a foreign body reaction if gets into the tissues below the skin

There are several ways of removing the hair, but all methods cause some skin trauma and inflammation. 




  • leaves minimal stubble 
    • causes multiple lacerations and skin erosions
  • associated with a 10-fold increase in surgical infections 
  • should NOT be used 


  • atraumatic 
  • do not work well on animals
  • expensive
  • frequent skin reactions, especially in cats



  • efficient 
  • relatively atraumatic
  • associated with lowest infection rates

Procedure for Clipping

  • Hair should NOT be clipped before anesthetic induction.
  • clipping is performed outside the surgical suite



  • clip at least 15 cm (6 in) around proposed incision (25 cm in large animals)  
  • if access to paw or hoof is not needed, cover rather than clip them 
    • these areas have higher resident bacterial populations
    • are difficult to clip without significant skin trauma
    • are difficult to effectively clean
  • hair is vacuumed
  • preliminary skin prep is performed before moving patient into surgery suite

Expressing the Bladder

Expressing Bladder

  • Animals should be walked to void before anesthesia is induced. 
    • minimizes messes and cleaning
  • the bladder is expressed under anesthesia to make the surgery easier
    • easier to work on the caudal abdomen (eg. uterine body)
    • minimizes voiding during surgery and subsequent wetting of the area
  • Technique
    • palpate bladder with one or both hands depending on size of animal
    • apply firm steady pressure to bladder
    • continue to apply pressure until bladder is empty (can be difficult to restart)

Transporting and positioning

  • patients should be moved on a trolley to the surgical site
  • circulating water heating pad* placed between the patient and table
    • minimize intra-operative hypothermia*
    • Do NOT use electric heating pads (erratic temperature control can result in severe burns)
    • other techniques to minimize heat loss include:
      • Warming intravenous fluids
      • Baer huggers
  • Position patient so have complete access to surgical site
    • Secure with ropes, adhesive tape or vacuum‑activated positioning bags *
  • Surgical site can then be prepped (scrub and final prep) 


  • prevent microorganism’s growth or action on living tissue by killing them or inhibiting their activity
  • effectiveness is measured by:
    • Immediate efficacy* (amount of skin microorganisms mechanically removed or inactivated within 3 minutes of applying).
    • Persistent antimicrobial effectiveness* (ability to prevent recolonization of skin up to 6 hours after applied).
    • Residual action* (cummulative antimicrobial effectiveness after used for at least 5 days)

Details on commonly used antiseptics

Mechanism of action: Increases bacterial wall permeability, precipitates cell contents

Required contact time: Maximal efficacy if > 2 minutes contact time

Spectrum: Broad spectrum (NOT non-enveloped viruses, spores or mycobacterium) 

Bacteriocidal Immediate action*: Rapid and very good

Bacteriocidal Persistent action*: Excellent

Bacteriocidal Residual action*: Excellent (Binds to stratum corneum*)

Toxicity: No systemic toxicity Occasional skin reaction Ototoxic (middle, inner) Neurotoxic (direct contact) Corneal toxicity if >2%

Other: Remains active with organic material

Mechanism of action: active agent is iodine Inhibits protein synthesis

Required contact time: Maximal efficacy if > 2 minutes contact time

Spectrum: Broad spectrum (spores only if > 15 minutes contact)

Bacteriocidal Immediate action*: Rapid and very good

Bacteriocidal Persistent action*: Good

Bacteriocidal Residual action*: None

Toxicity: Acute contact dermatitis (50% of small animals) Thyroid dysfunction? Can absorb toxic amounts from mucus membranes, peritoneal surfaces and large open wounds

Other: Inactivated by organic material (eg. blood, pus) More effective if diluted Economical

Mechanism of action: Damages lipid in cell wall, precipitates proteins, inhibits mitosis

Required contact time: (before alcohol evaporates)

Spectrum: Broad spectrum (NOT spores)

Bacteriocidal Immediate action*: Very Rapid and excellent

Bacteriocidal Persistent action*: Very Good

Bacteriocidal Residual action*: Some (continued death of damaged organisms)

Toxicity: Nontoxic if intact skin (can dry & irritate skin) Cutaneous absorption in neonates, none adults Tissue necrosis in open wounds

Other: Increases initial kill by chlorhexidine and iodophors, More effective if diluted

Skin preparation

Goal: to make the skin surgically clean

  • not possible to sterilize
    • approximately 20% of skin bacteria are in deeper skin layers protected from exposure to the antiseptic
    • these bacteria will migrate to surface over time and progressively repopulate the area

Keeps the OR as clean and dry as possible

This causes irritation and abrasions that will be rapidly colonized by bacteria resulting in increased infection rates.

This causes hypothermia in the patient and wetting of the cloth surgical drapes leading to strike-through.

This is because the peripheral region is the dirtiest. This procedure minimizes the number of bacteria on the central area where the incision is planned.

This is the minimum time required for most antiseptic scrubs to obtain maximal bacterial kills. If the gauze is visibly dirty after completing a pass, the site is considered contaminated no matter how much time has passed. Scrubbing should continue until the gauze remains clean).

Alcohol is a drying agent helping to dry the skin as well as an antiseptic that increases the total number of microorganisms killed.