Rodent Survival Surgery: Post-operative infections in rodents can and do occur. Such infections, which may not be apparent on casual observation, may cause distress to the animals and may affect the results of a study.
Aseptic surgical procedures must always be used in animal surgeries, regardless of species, however this does not always mean complete gown, mask, in a surgical suite. A separate room used primarily for aseptic procedures is desirable; however, a survival rodent surgical procedure in a conventional laboratory setting using aseptic technique is acceptable.

The minimum standards for aseptic procedures in rodents done in investigator laboratories are:

• A clean uncluttered work area, away from break areas and out of the human traffic flow, for the pre-procedure, procedure, and post-procedure recovery. This can be the same or proximate area.

• A disinfected work surface. Use Clidox, Chlorhexidiene, Clorox, quaternary ammonia, or hydrogen peroxide as a surface wipe down prior to placing the animal on the work area. Alcohol, as a sole surface disinfection, is not appropriate.

• Use only in-date anesthetics and analgesics. If volatile (inhaled) anesthetics are being used, an appropriate scavenging system must be in use.

• Monitoring of depth of anesthesia must be part of the process. Remember, the palpebral reflex is not consistent in rodents and should not be a primary means of assessing depth of anesthesia. Use the pedal reflex instead.

• Supplement anesthetic, as necessary, to maintain anesthesia. Remember, if using Ketamine and Xylazine as your anesthetic regimen, you do not supplement with Xylazine as this drug has a long metabolism and additional supplementation will likely delay recovery or could kill the animal. If using Ketamine / xylazine anesthesia, supplement only with Ketamine.

• Appropriate preparation of the surgical site including removal of the hair and disinfection of the skin. The 'standard of care' for the Duke animal care program includes the use of an iodine (or chlrohexidine) skin scrub followed by an alcohol rinse a total of three times. With IACUC approval, alcohol may be used as a sole skin disinfection agent, if necessary.

• Draping the surgical site with sterile drapes to avoid contamination of the incision, instruments, and supplies; or the use of sterile toweling to rest surgical instruments between uses. 

• If appropriate precautions are taken to minimize contamination of surgical gloves, it is adequate to rinse the gloves with a sterilant between rodents. If surgical gloves become contaminated by handling non-sterilized items, they will be replaced with sterile gloves. 

• A surgical mask should be worn by the surgeon and any assistants working in the immediate surgical field. Additional personal protection equipment (PPE) may also be used as desired. 

• A hair cover (surgical cap) should be worn by the surgeon to prevent loose hair from falling into the open wound. 

Heat supplementation (for the animal) for procedures lasting more than 15 minutes is usually required. Do not lay the animal directly on a heating blanket, but place 2 or more layers of toweling over the electric blanket and then place the animal on the toweling. This prevents severe burns that can occur with electric blankets or other heating devices.

The use of sterile instruments, sterile supplies (for internal use), and proper wound closure materials are required (See below for proper methods of sterilization).

Post procedural recovery should include a quiet location, that is warm (may use heating pad or lamp), and where the animal can be readily observed by the technician (in case of distress during recovery). This location may or may not be the surgery area. 

Controlled Substances: 

• Maintain proper control and administrative record keeping by record keeping by recording the date, time, animal identification, dose, resulting balance, and a signature of the individual administering the dose.

• Maintain the drug in a locked storage drawer, cabinet, or safe.
   

Using Sterile Instrument in Rodent Surgery:  Surgical procedures may be performed on multiple rodents during a single session using one sterile surgical pack, providing care is taken to minimize contamination and re-sterilization of the instrument tips between animals (as long as you do not touch the tips, your ‘sterile’ gloves may be used for multiple animals). The tip is the part of the instrument that actually touches the tissue / organ, therefore, for rodent surgery, the tip MUST be sterile, the rest MUST be clean.

Methods to sterilize the instruments (tips) are:

• Initial Instrument Preparation:

  • Autoclave instruments using appropriate wrapping material and heat sensitive tape / indicator, or
    Wash the instrument with standard kitchen detergent and dry with a clean cloth. 'Flame' instrument tips with 95% alcohol or  heat the instrument tips in a glass bead sterilizers (approximately 15 seconds) and then cool the instrument tip using sterile saline or sterile air for 30 – 45 seconds before use. Store with tips sterile until use.

  • Soak instruments in a 'cold' seterilant:

    • Benz-all (single use size): Mix one bottle in one gallon of water. Soak for a minimum of 5 minutes before use.

    • Amerse: Mix 1 ounce per gallon of water. Soak for a minimum of 5 minutes before use.

    • Cidex: Active ingredient: 2% Glutaraldehyde. The manufacturer's instructions indicate that a minimum of 10 hours is required for sterilization. Cidex comes in two formulations, Cidex and Cidex-7 (long-life). The shelf life of activated Cidex is 15 days and of activated Cidex-7 is 28 days. Clidox: Active ingredient: Chlorine dioxide. 1:5 mixture must be mixed daily. 1:18 mixture is good for 14 days. 1:5 is a good sterlant; 1:18 is a disinfectant. 

    • Alcide: Active ingredient: Sodium hypohlorite 1.37%. The manufacturer's instructions indicate that a minimum of 6 hours is required for sterilization. The shelf life of the activated solution is 14 days. 

    Other acceptable sterilants are the following chemicals classified as sterilants by the Centers for Disease Control (CDC). These are the chemical ingredients of some of the commercial sterilants: 

    • Glutaraldehyde (2%) for a minimum of 10 hours

    • Formaldehyde (8%) / Alcohol (70%); minimum of 18 hours

    • Stabilized hydrogen peroxide (6%) for a minimum of 6 hours

    • Soaking in alcohol IS NOT APPROVED! Alcohol is not classified as a high level sterilant!

  Between Animal Re-Sterilization: Surgical procedures may be performed on multiple rodents during a single session using one sterile surgical pack, providing care is taken to minimize contamination and re-sterilization of the instrument tips between animals (as long as you do not touch the tips, your ‘sterile’ gloves may be used for multiple animals). The methods to accomplish this include:

  • 'Flame' instrument tips with 95% alcohol or  heat the instrument tips in a glass bead sterilizers (approximately 15 seconds) and then cool the instrument tip using sterile saline or sterile air for 30 – 45 seconds before use. Store with tips sterile until use.

  • Benz-all: Soak for a minimum of 5 minutes between uses.

  • Amerse: Soak for a minimum of 5 minutes between uses.

  • Cidex: Soak for a minimum of 5 minutes between uses.