Surgery Requirements in Laboratory Animals PDF

# Surgery Requirements in Laboratory Animals ## Surgical Definitions * **Survival surgery:** Animal recovers from the procedure and anesthesia. This surgery requires aseptic procedures, including surgical gloves, masks, sterile instruments, and aseptic technique. * **Terminal, acute, or non-surviv...

# Surgery Requirements in Laboratory Animals ## Surgical Definitions * **Survival surgery:** Animal recovers from the procedure and anesthesia. This surgery requires aseptic procedures, including surgical gloves, masks, sterile instruments, and aseptic technique. * **Terminal, acute, or non-survival surgery:** Animal is humanely euthanized while still under anesthesia. Certain principles of asepsis may not apply depending on the procedure length. * **Major surgical procedure:** Surgery that penetrates and exposes a body cavity or any procedure that permanently impairs physical or physiological functions (e.g., laparotomy, thoracotomy, craniotomy, amputations). * **Minor surgical procedure:** Surgery that does not penetrate or expose a body cavity or permanently impair physical or physiological functions (e.g., subcutaneous osmotic pump placement, skin biopsy). ## Facilities Requirements ### Dedicated Workspace * **Defined as an area within the lab that is free from unnecessary equipment and materials.** * Easily subitizable, and has limited traffic flow during procedures. * **Hood space protecting patient is optimal.** * **Species/procedures allowed:** Survival surgery in mice, rats, hamsters, guinea pigs, and non-mammals; non-survival surgery in any species; and minor procedures in any species. * **Guidance:** At the time of surgery, postpone all other laboratory work. ## Dedicated Surgical Room * **Defined as a room designed for surgical procedures that maintains the appropriate environmental conditions, sanitation standards, and dedication to surgical procedures.** * **Species/procedures allowed:** Mammals larger than guinea pigs undergoing a major survival procedure. * **Guidance:** Periodically clean floors, walls, and other surfaces within the room in addition to the immediate surgical area. * **Limit non-surgical room use to prevent contamination.** ## Preparation & Procedures * **Pre-Operative Preparation** * **Intraoperative Procedures** * **Anesthetic Recovery & Post-Operative Procedures** * **Acute or Non-Survival Surgery Exceptions** ## Surgical Instruments * **Pre-procedure:** Sanitize and sterilize all instruments prior to starting a surgical procedure. * **Storage:** Date and store unused packs for up to six months. After six months, surgical packs need to be repackaged and resterilized before use. * **Primary sterilization:** Accomplish this through any of the following methods: * **Pressurized steam (autoclave):** This is the most common sterilization procedure for surgical instruments, and is accomplished by placing instruments in appropriate containment for autoclaving and storage. Examples include placing instruments in self-sealing autoclave. ## Pre-Operative Preparation * **Pre-operative considerations are an important part of planning surgical procedures.** * **Consider four main areas when preparing a surgical procedure:** * **Surgical space, instruments, surgeon, and animal.** * **Surgical Space: Workspaces & Surgical Rooms** * **Disinfecting:** Regardless of the type of facility or space, clean and disinfect all surfaces necessary for the surgical procedure using appropriate disinfectants (e.g., diluted bleach, hydrogen peroxide products such as Rescue, or similar products with broad disinfectant efficacy). * **Traffic flow:** During surgical procedures, limit traffic to the individuals necessary for the surgical procedure. ## Carefully monitor expiration dates of prepared solutions, as many are only good for short periods of time after activating. In addition, rinse all instruments with sterile water or saline immediately before use to prevent tissue toxicity. * **Reuse:** Use newly sterilized instruments and materials for every animal. * **Replacements:** Immediately replace instruments anytime they fall outside the sterile field or become contaminated (e.g., use in intestinal surgery). ## Pouches or stainless steel trays wrapped in surgical paper designed for autoclaving. * **Ethylene oxide (gas sterilization):** Commonly used for sensitive equipment or instruments. * **Cold sterilization:** Strictly adhere to the manufacturer's directions for sterilization. If contact times or dilutions are not followed exactly, it may only disinfect instruments rather than sterilize them. ## Animal * **Location:** Prepare animals for surgery away from the designated surgical space or room. * **Hair removal:** * Remove hair from the surgical site and surrounding area to prevent contamination . * Generally, the hairless area should be two to three times the size of the anticipated surgical field. * Remove hair by using an electric clipper or depilatory cream (rodents). * The best practice is to remove hair immediately prior to surgery. ## Surgeon * **Pre-scrubbing:** Prior to scrubbing, don all non-sterile surgical items including facemasks, hairnets, shoe covers, etc. * **Scrubbing:** Wash/scrub hands and arms thoroughly with an appropriate surgical scrub (e.g., iodine or chlorhexidine products). * Scrub hands for at least five minutes moving from fingertips to elbows. * Scrubbing multiple times is acceptable to reach the appropriate contact time. * **Rinse and dry with a sterile towel prior to donning surgical attire.** ## Skin preparation: * Scrub the skin surrounding the animal's surgical site with an appropriate disinfectant (iodine or chlorhexidine scrubs) and 70% alcohol combination. * Scrub the area no less than three alternating scrubs with disinfectant and 70% alcohol. * Work from clean to dirty: Scrub starting at the center of the surgical site and then slowly work toward the periphery of the surgical field, making sure not to move backwards. * Do not use chlorhexidine-based scrubs on or around eyes. * Consult your veterinarian regarding skin preparation in aquatic species. ## Drapes or sterile coverings: * Prior to initiating surgery, place a sterile drape over the animal with access to the surgical site, unless the species or surgical procedure makes this difficult (e.g., mice). * Drapes may be paper, cloth, or plastic products, as long as they are sterile and allow for monitoring the patient under anesthesia. ## Surgical attire: * Appropriate surgical attire includes a cap/hair cover, surgical facemask, shoe covers, and sterile gown. * Surgery on rodents and other small species does not always require full surgical attire. * If performing surgery on rodents inside a biological safety cabinet, hair cover and surgical facemask are not required. * If aseptic technique is broken, change the affected article immediately prior to continuing with surgery (e.g., new gown or surgical glove). ## Post-scrubbing: * After scrubbing, done all sterile attire – including the sterile gown and sterile surgical gloves - using aseptic technique. ## Intraoperative Procedures * Using appropriate intraoperative technique is essential for a good surgical outcome. * This involves maintaining aseptic technique and conscientious tissue-handling during surgery. ## Basics for a successful surgery: 1. **Assessing and ensuring appropriate anesthetic depth** 2. **Aseptic technique procedure** 3. **Appropriate tissue-handling** 4. **Closure procedures** ## Aseptic technique procedure * Keep hands within the sterile field created by the drape or instrument tray. * If you touch areas outside the sterile field or if a glove breaks, immediately change the contaminated article (e.g., gloves, gown). * Carefully place instruments to maintain sterility. * Immediately replace contaminated instruments . * Keep surgical drapes clean, dry, and in place to provide appropriate protection. * Keep the drape in place using towel clamps, sutures, or adhesives. * Remove these carefully to prevent injury to the animal's skin. ## Appropriate tissue-handling * Limited, gentle handling of tissues is essential to prevent infection, delayed healing, and incision site dehiscence. * **Examples of gentle handling include using a traumatic forceps during organ manipulation and periodically wetting exposed abdominal organs.** ## Assessing and ensuring appropriate anesthetic depth * Prior to initiating surgery, confirm the appropriate anesthetic depth * **by checking the reaction to stimuli (e.g., toe pinch, palpebral reflex), body tone (e.g., jaw tone in swine)** * **And physiologic parameters (e.g., heart rate, respiratory rate, etc.).** * **Use multiple parameters to assess depth.** ## Closure procedures * **Appropriate suture size, type, and closure pattern are necessary to prevent dehiscence and delayed healing.** * Please discuss any questions about size, type, or pattern prior to surgery with the veterinarian. ## Size * **Appropriate size will vary by species and tissue.** * **For example, skin closure in a mouse will require a 5-0 or 4-0 gauge, whereas skin closure in a dog will require a 3-0 or 2-0 gauge.** ## Pattern * **The most commonly used suture pattern is the simple interrupted closure.** * **It is good for tissue apposition, holds the incision closed even when a few sutures fail, and can be used for most situations.** * **In high-tension areas (e.g., around limbs, on head), other patterns may be more suitable.** ## Type * **Suture type is dictated by the surgical site and tissues involved.** * **(absorbable vs. non-absorbable):** * **Absorbable sutures are most commonly used within tissues, as they don't have to be removed.** * **Non-absorbable sutures are most commonly used in skin and are removed in 7-14 days.** * **Composition (monofilament vs. braided)** * **Monofilament sutures are recommended for skin closure because they don't wick bacteria.** * **Braided sutures tend to wick bacteria and should not be used in skin or in organs where contamination may be present (e.g., intestine, bladder).** ## Analgesia * **Provide post-procedure analgesia per the IACUC-approved protocol.** * **Consult with your area veterinarian if animals show signs of unrelieved pain after receiving analgesics.** * **View recommended analgesics, doses, and guidelines.** ## Surgical site monitoring and suture/staple removal * **Observe and record the animal's post-operative health and surgical site for a minimum of three days.** * **This is only the required minimum; post-surgical monitoring may be needed for longer time periods in more severe surgical cases or if complication arise.** * **Remove sutures or wound clips from the skin 7-14 days after surgery.** * **Veterinary staff recommend that sutures in large species stay in for >10 days.** * **Record the date of suture or staple removal in the animal's health record.** * **This is often the last health record entry for animals that have otherwise healed from their procedure.** ## Anesthetic Recovery & Post-Operative Procedures ### 1. Anesthetic recovery * **Upon completing the surgical procedure, monitor animals during recovery from the anesthetic event.** * **This is a critical time; careful monitoring may prevent unintended complications.** * **Provide appropriate recovery conditions including a warm environment free from objects that could cause harm.** * **For example, use paper towels instead of corn cob bedding when recovering rodents, and remove large toys or water bowls from large animal pens.** * **Record recovery notes and stay with the animal until it is fully ambulatory and able to reach food and water.** ## Anesthetize animal, administer analgesia * **Apply ophthalmic ointment to both eyes** * **Remove hair (shave, pluck, and/or Nair)** * **Repeat above three times with a new pad/swab each time** * **Remove loose hair and visible dirt/debris** * **Apply betadine or chlorhexidine scrub/solution, circling from incision site ** * **Wipe away scrub/solution with 70% alcohol or sterile water/saline, circling outward** * **Cover animal with a sterile drape, ensuring visibility for monitoring**