How to Clean and Sterilize Veterinary Surgical Instruments Properly

The sterility of veterinary surgical instruments is not a background consideration. It is an active, ongoing requirement that determines whether every procedure begins with the safest possible conditions for the patient. Contaminated instruments carry pathogens directly into the surgical field, where tissue trauma and disrupted local immunity create the ideal environment for infection to establish. The consequences range from delayed wound healing and surgical site infection to systemic sepsis in vulnerable patients.

Proper cleaning and sterilization of veterinary surgical instruments requires a structured, consistent process that accounts for the biological soil left on instruments after use, the method of sterilization appropriate for each instrument type, and the storage and handling protocols that preserve sterility until the instrument is used. This guide covers each step of that process in detail.

Why Instrument Sterilization Matters in Veterinary Surgery

The Relationship Between Instrument Sterility and Surgical Outcomes

Every contact between a non-sterile surface and the surgical wound increases the patient's risk of infection. Surgical site infections in veterinary patients extend healing timelines, require additional treatment, and in severe cases can be life-threatening. The majority of surgical site infections are preventable through rigorous aseptic technique, and instrument sterilization is the foundation of that technique.

The single-use design of many modern veterinary closure products, including disposable skin staplers and pre-packaged veterinary surgical sutures, eliminates the reprocessing variable for those items entirely. Reusable surgical instruments, however, require validated cleaning and sterilization between every use to deliver the same sterility assurance.

What Contamination Looks Like on Used Instruments

After a procedure, reusable veterinary surgical instruments carry several categories of contaminating material. Organic soil including blood, tissue fragments, bone dust, and body fluids represents the most significant contamination challenge. Microorganisms including bacteria, fungi, and in some contexts viral particles are present in and on this organic soil. Inorganic residues from irrigating solutions and chemical agents used during the procedure may also be present.

All of these must be removed before sterilization is attempted. Sterilization processes are designed to kill microorganisms on a clean surface. They are not designed to penetrate and disinfect through a layer of organic material. Instruments that are sterilized without adequate prior cleaning may emerge from the sterilizer with a sterile outer surface over residual organic soil that contains viable microorganisms.

Step 1: Immediate Post-Procedure Handling

Why Speed Matters After Use

The most important principle of instrument cleaning is that it should begin as soon as possible after the procedure. Blood and tissue fluid dry rapidly on metal surfaces, particularly in a warm operating room environment. Dried organic soil is significantly harder to remove than fresh soil and may not be fully eliminated even by thorough manual cleaning. Soaking or rinsing instruments immediately after use prevents this drying and protects the quality of all subsequent cleaning steps.

Pre-Cleaning at the Point of Use

Immediately after each procedure, instruments should be wiped with a moist cloth or rinsed under cold water to remove the bulk of visible soil before they leave the operating field. Hot water should not be used at this stage because it can coagulate proteins in blood and tissue fluid, fixing them to the instrument surface and making removal more difficult.

Sharps including needle holders with attached needles and suture scissors should be handled with particular care during this initial handling step. Contaminated sharps should be passed carefully into dedicated sharps containers or placed in a designated secure area of the instrument tray for controlled transport to the cleaning area.

Step 2: Manual Cleaning

Soaking

Instruments transported to the cleaning area should be placed in an appropriate enzymatic detergent solution formulated for surgical instrument cleaning. These detergent solutions contain proteolytic, lipolytic, and amylolytic enzymes that break down the protein, fat, and carbohydrate components of organic soil, making it easier to remove mechanically. Soaking time varies by product but is typically 10 to 15 minutes at the concentration and temperature specified by the manufacturer.

Hinged instruments such as needle holders, haemostatic forceps, and tissue forceps should be soaked in the open position to allow detergent access to the box lock, ratchet, and any other complex internal surfaces where soil can accumulate. Tubular instruments and cannulae should be flushed with detergent solution to ensure internal surfaces are reached.

Brushing

After soaking, each instrument should be scrubbed manually under the detergent solution surface, not above it, to prevent aerosolisation of contaminated material. A soft brush appropriate for the instrument type should be used to scrub all surfaces including box joints, serrations, teeth, and the jaws and tips of all instruments. Scrubbing above the solution line is a common technique error that creates aerosol droplets containing biological material, which represent both a contamination and an occupational safety risk.

Special attention should be paid to the box lock of hinged instruments, where organic soil accumulates most persistently and is most likely to compromise the cleaning result. Ultrasonic cleaning provides a valuable adjunct to manual brushing in this area.

Rinsing

After manual scrubbing, instruments must be thoroughly rinsed under running water to remove all traces of detergent and loosened soil. Detergent residue left on instruments can interfere with sterilization processes and may cause tissue irritation if carried into the next procedure. Instruments with lumens or complex internal channels should be flushed under positive pressure to ensure complete rinsing of internal surfaces.

Step 3: Ultrasonic Cleaning

How Ultrasonic Cleaners Work

Ultrasonic cleaning devices transmit high-frequency sound waves through a liquid medium, producing millions of microscopic cavitation bubbles that collapse with intense localised energy. This cavitation dislodges soil from instrument surfaces and from complex internal geometries that manual brushing cannot consistently reach, including serrations, box joints, and the channels of complex instruments.

When to Use Ultrasonic Cleaning

Ultrasonic cleaning is particularly valuable for instruments with complex surfaces and fine serrations where manual brushing is mechanically limited. Needle holders, haemostatic forceps, and tissue scissors benefit significantly from ultrasonic processing. Instruments should be placed in the open position in the ultrasonic bath in an appropriate enzymatic cleaning solution, and the bath should be used at the temperature and cycle time recommended by the manufacturer.

Ultrasonic cleaning does not replace manual cleaning but complements it, addressing the residual soil that manual techniques may leave in inaccessible areas. Instruments that have been manually cleaned and then ultrasonically processed have a lower residual soil burden than those subjected to either technique alone.

Step 4: Inspection and Maintenance

Visual Inspection

After cleaning and before sterilization, each instrument should be inspected visually under adequate lighting. Inspection checks for residual soil, corrosion, damage to working surfaces, and mechanical function. Any instrument with visible residual soil must be returned to the cleaning process rather than proceeding to sterilization.

Hinged instruments should be tested for smooth opening and closing, appropriate ratchet function, and jaw alignment. Scissors should be checked for clean cutting without catching or tearing. Needle holders should be checked for jaw closure quality and ratchet engagement. Instruments that fail functional inspection should be removed from service and assessed for repair or replacement.

Lubrication

After cleaning and inspection, hinged instruments should receive appropriate instrument lubricant before sterilization. Instrument lubricants maintain the mechanical function of box joints and ratchet mechanisms and protect against the corrosive effect of steam sterilization cycles on metal components over time. Water-soluble lubricants designed for instrument processing should be used, as oil-based lubricants can interfere with sterilization penetration. The lubricant should be applied by soaking or spray as directed by the product manufacturer, and excess should be drained rather than wiped off.

Step 5: Packaging for Sterilization

Why Packaging Matters

Instruments must be packaged before sterilization to maintain the sterility of the processed instruments from the sterilizer to the point of use. The packaging allows the sterilizing agent to penetrate during the cycle while preventing recontamination after the cycle is complete. The choice of packaging material must be compatible with the sterilization method being used.

Packaging Options

Sterilization pouches made from paper-plastic or non-woven material are appropriate for individual instruments or small sets. Double pouching, placing one sealed pouch inside another, is recommended for items where maintaining sterility through extended storage is important. Sterilization wrap, applied in a double-wrap configuration, is used for larger instrument sets and trays.

All packaging should be sealed correctly according to the manufacturer's instructions and labelled with the sterilization date, cycle number or batch identifier, and expiry date for the sterility period applicable to that packaging type and storage environment. Internal and external chemical indicator strips should be included in every package to provide visual confirmation that the package has been exposed to the sterilization process.

Step 6: Sterilization Methods

Steam Autoclave Sterilization

Steam autoclaving is the most widely used method of sterilizing surgical instruments in veterinary practice and is considered the gold standard for heat-stable, moisture-tolerant instruments. The autoclave uses pressurised saturated steam to achieve temperatures that destroy all microorganisms including bacterial spores, which are the most resistant life forms the sterilization process must address.

The two most common autoclave cycle parameters used in veterinary practice are the gravity displacement cycle at 121 degrees Celsius for 15 to 30 minutes and the pre-vacuum or porous load cycle at 134 degrees Celsius for 3 to 4 minutes. The pre-vacuum cycle is more effective for porous loads and complex instruments because it actively removes air from the chamber before steam entry, ensuring steam penetration into all areas of the load including fabric wrapping, complex instrument joints, and porous packaging materials.

Correct loading of the autoclave is as important as correct cycle selection. Instruments should be arranged so that steam can circulate freely around each package. Containers must allow steam entry and condensate drainage. Overloading the autoclave restricts steam circulation and may result in inadequately sterilized items even when the cycle parameters appear correct on the printout.

Dry Heat Sterilization

Dry heat ovens can be used for instruments that would be damaged by moisture but are heat-stable. The standard dry heat cycle operates at 160 degrees Celsius for two hours. Dry heat sterilization is less efficient than steam because heat transfer through dry air is slower than through steam, and higher temperatures and longer exposure times are required to achieve equivalent microbial destruction. It is used primarily for glassware, oils, and powders rather than for routine surgical instrument sterilization in most veterinary settings.

Chemical and Low-Temperature Sterilization

Instruments that cannot tolerate heat, including some powered surgical instruments and complex optical equipment, require low-temperature sterilization methods. Ethylene oxide gas sterilization and hydrogen peroxide plasma sterilization are the most commonly available options in larger veterinary hospital settings. These methods require dedicated equipment, specific packaging materials compatible with the method, and appropriate aeration time after processing to remove chemical residues before the instrument can be used safely.

Sterilization Monitoring

Sterilization cycles should be monitored using a combination of physical indicators on the autoclave printout, chemical indicators that change appearance on exposure to the sterilizing conditions, and biological indicators that use bacterial spores to confirm that the process is achieving the microbial destruction it is designed to produce. Biological indicator testing should be performed on a scheduled basis according to the practice's quality assurance programme, with results documented and retained.

Step 7: Storage and Handling After Sterilization

Maintaining Sterility in Storage

Once sterilized packages have been removed from the autoclave and cooled completely, they must be stored in conditions that maintain their sterility until they are needed. Storage areas should be clean, dry, and protected from dust and physical damage. Packages should not be stored in areas where moisture can condense on them, as moisture compromises packaging integrity and creates conditions for microbial growth.

Packaged sterile instruments should be stored on shelving with adequate clearance from the floor, walls, and ceiling. Items should be rotated on a first-in, first-out basis to ensure that older sterilization dates are used before more recently processed items. Sterility is considered event-related in most modern infection control frameworks, meaning that sterility is maintained as long as the package integrity is maintained and the item is stored correctly, rather than being determined solely by a fixed calendar date.

Inspection Before Opening

Before any sterile package is opened for a procedure, the packaging should be inspected for integrity. Torn seals, punctures, moisture damage, or wet packages should result in the package being returned to reprocessing rather than being used. External chemical indicators should show the expected colour change confirming sterilization exposure. If there is any doubt about the integrity of the package, it should be considered non-sterile and not introduced to the surgical field.

Handling Veterinary Surgical Sutures and Closure Products in the Sterile Field

Single-Use Sterile Products

Unlike reusable instruments, veterinary surgical sutures, disposable skin staplers, and veterinary tissue adhesive products are supplied pre-sterilized in sealed packaging designed for single use. These products arrive sterile and do not require any reprocessing before use. The sterility of these items is maintained by packaging integrity and should be confirmed by visual inspection before each use.

Suture packaging that is torn, punctured, or shows signs of moisture damage should be discarded without being used, as packaging integrity is the only guarantee of sterility for these single-use items. For guidance on correct sterile transfer of suture materials to the surgical field, see How to Prepare Suture Materials for Veterinary Soft Tissue Surgery.

Transferring Products to the Sterile Field

The transfer of pre-packaged sterile products from outer packaging to the sterile field is a point where contamination can occur if technique is not correct. The circulating nurse should peel back the outer packaging using a smooth controlled motion without allowing the exterior surface to contact the sterile field. The inner sterile item should be presented to the scrub technician in a way that allows it to be received without any contact between the outer packaging surface and the sterile field or the scrub technician's sterile gloves.

Veterinary Tissue Adhesive Storage and Use

Veterinary tissue adhesive products such as medical-grade cyanoacrylate skin glue require correct storage to maintain their performance before opening and correct technique during application to avoid cross-contamination and accidental adhesive bonding. Adhesive products should be stored in cool, dry conditions as directed by the manufacturer, tightly capped between uses, and inspected before use for signs of partial polymerization in the applicator that would indicate compromised product. For detailed guidance on the correct use of tissue adhesive in veterinary wound closure, see Surgical Glue for Skin: Techniques a Vet Surgeon Should Know.

Common Sterilization Errors and How to Avoid Them

The Role of Consistent Protocols in Veterinary Practice

Sterilization quality in a veterinary practice depends not just on having the correct equipment but on having consistent written protocols that every team member follows identically on every occasion. A protocol that produces sterile instruments reliably when followed perfectly but is not consistently followed by all staff on all occasions does not achieve the infection control standard the practice needs.

Written standard operating procedures for each step of the instrument reprocessing pathway should be accessible in the cleaning and sterilization area. New staff should be trained against these procedures before working independently. Regular review and audit of compliance helps identify the small deviations in technique that can develop over time and gradually compromise the reliability of the sterilization outcome.

Sterile Instruments, Safer Patients

Properly cleaned and sterilized veterinary surgical instruments are a non-negotiable prerequisite for safe surgery. Every patient who undergoes a procedure in a veterinary facility deserves the assurance that the instruments entering their body have been reprocessed to a validated and consistent standard. The steps described in this guide, immediate post-use handling, manual cleaning, ultrasonic processing, inspection, packaging, validated sterilization, and correct storage, together constitute a sterilization pathway that reliably delivers that assurance when followed consistently.

Gexfix International Corp., in partnership with Assut Europe S.P.A., supports veterinary practices with a comprehensive range of single-use sterile closure products including ASSUFIL® PGA and PDS monofilament veterinary surgical sutures, ASSUNYL® Nylon, FILBLOC® Barbed Sutures, disposable skin staplers, and veterinary tissue adhesive. Each product arrives pre-sterilized and validated to ISO 13485 production standards, providing the consistent sterility assurance that reusable instrument reprocessing aims to match. With over 30 years of manufacturing expertise, Gexfix ensures that veterinary professionals have access to the high-quality single-use surgical products that support safe, infection-controlled veterinary practice.

Explore the full range at medicaldevicevet.com.

FAQs

Q. What is the correct order of steps for sterilizing veterinary surgical instruments?

A. The correct order is: immediate post-use rinsing, manual cleaning with enzymatic detergent, ultrasonic cleaning, thorough rinsing, visual inspection, lubrication, packaging, and then sterilization by the appropriate validated method. Skipping or reversing steps reduces the reliability of the sterilization outcome.

Q. Can veterinary surgical sutures and disposable staplers be sterilized and reused?

A. No. Veterinary surgical sutures, disposable skin staplers, and tissue adhesive products are single-use items supplied pre-sterilized. They must not be resterilized or reused. Only reusable instruments designed for reprocessing should enter the sterilization cycle.

Q. Why must instruments be cleaned before sterilization?

A. Sterilization kills microorganisms on clean surfaces but cannot penetrate through layers of organic soil. Blood, tissue, and fluid residue on an instrument surface protect the microorganisms beneath from the sterilizing agent, meaning sterilization without prior cleaning does not reliably produce a sterile instrument.

Q. How long do sterilized instrument packages remain sterile in storage?

A. Sterility is event-related rather than time-limited in most current infection control frameworks. Packages remain sterile as long as packaging integrity is maintained and storage conditions are correct. Torn, wet, or punctured packages should be considered non-sterile regardless of the sterilization date.

Q. What should be checked on a sterile package before it is opened for a procedure?

A. Check that the packaging is intact with no tears, punctures, or moisture damage. Confirm that external chemical indicators show the expected colour change confirming sterilization exposure. If any aspect of the package condition raises doubt about its integrity, do not use it and return it to reprocessing.