IACUC Learning Module - Surgery

IACUC Learning Module - Surgery, Anesthesia - Vertebrate Species

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Definitions of Commonly Used Terminology

Analgesic - a drug which causes an absence of pain in response to stimulation which would normally be painful; often, what is actually achieved following administration of an analgesic is hypoalgesia, or diminished pain in response to a stimulus.

Anesthesia Definitions

  • Anesthesia, general - provides overall insensitivity and unconsciousness.
  • Basic elements of general anesthesia include:

  • unconsciousness
  • amnesia (loss of memory of pain or distress)
  • analgesia
  • muscle relaxation
  • diminished motor response to noxious stimuli
  • reversibility
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  • Anesthetic - a drug which causes a reversible loss of conscious awareness and sensation, including pain.
  • Neuromuscular blocking agent (paralytic agent) - a drug which blocks transmission at the neuromuscular junction; these drugs lack anesthetic and analgesic properties. It is illegal to use a neuromuscular blocking agent for painful procedures, unless anesthetics or analgesic drugs are used in conjunction. Mechanical ventilation must be provided.
  • Sedative - a drug which produces a state of decreased motor activity, mental calmness, and drowsiness; does not imply analgesia, although most sedatives will increase the pain tolerance threshold by reducing anxiety and fear.
  • Anesthetic Management Principles - Prevention of perceived pain during surgery is the primary function of anesthesia.

  • Anesthesia also enables humane restraint, improves safety, and increases technical efficiency. Although many factors affect choice of a particular anesthetic drug or technique, the greatest concern must be the well-being of the animal.
    • A general rule of thumb is "aim only for the degree of restraint and anesthesia required" - more may not be better and often is associated with a greater potential for adverse effects.

    Aseptic procedures - All of the techniques and practices employed to prevent microbial contamination of the surgical site. These include: removal of hair from the surgical site, use of surgical scrub and sterile draping of the area. Sterile instruments, proper attire, and adherence to current operating room policy are required.

    Major Surgery – Any surgical intervention that penetrates and exposes a body cavity Or any procedure that is likely to produce a permanent impairment of physical movement or basic physiological function, And/Or any procedure associated with orthopedics or extensive tissue dissection or transaction.

    • Major survival surgery for warm-blooded "higher" vertebrate animals such as rabbits, dogs, cats, pigs, sheep, or monkeys must be performed in dedicated facilities specifically designed, operated, and maintained for that purpose. Cold-blooded vertebrate or rodent surgeries may be performed aseptically in a clean, non-dedicated room or laboratory. Farm-type procedures may be performed at the agricultural center. Surgical procedures on wild animals, both major and minor may be performed in the field but aseptic principles must be followed. The IACUC approves the appropriate site for specific operative procedures.

     

    • Use of one animal in multiple major survival surgeries is allowed only when such procedures are related components of a protocol; they must be scientifically justified in the protocol and approved by the IACUC. Cost savings is not an acceptable justification for multiple major survival surgeries on any animal. Determination that a procedure constitutes major surgery is usually made during the IACUC review process. However, development of "permanent physical or physiologic impairment" may not be recognized until after the procedure is performed. If such impairment develops after a surgery, that animal cannot be used for another recovery procedure.

     

    • If the second major procedure is non-survival, this is not considered to be multiple major survival surgery.

    Minor Surgery – Any surgical intervention that does not penetrate a body cavity nor expose a body cavity, or causes little or no physical or physiologic impairment (e.g. wound suturing, peripheral vessel cannulation, laparoscopy, percutaneous biopsy).

    • A dedicated surgical facility is not required for such procedures, however, the surgical area should be clean and aseptic techniques must be observed. For minor survival surgery procedures, there is no prohibition against multiple procedures. Good professional judgment should be used to limit the number of minor surgical procedures performed on a single animal.

    Non-Survival Surgery - Surgery from which the subject does not regain consciousness from anesthesia prior to being euthanized.

    Preoperative Management Principles - The well-being of the animal and validity of the study are enhanced by proper management before the operative procedure.

  • Animal health status - The health status of animals should be assessed before undergoing a surgical procedure. Evaluation of blood, urine, and feces can be helpful, depending on the animal species and health history of the animal or colony. Health assessments are usually conducted during a quarantine period when the animals are kept separate from conditioned animals. The quarantine period of random source animals is generally a few weeks duration, in part since these animals may need to be immunized against common infectious diseases. Purpose bred animals also require quarantine, but the period is much shorter.
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  • Conditioning - It is important that animals be provided a period of adaptation prior to undergoing surgical procedures. This allows the animal's physiologic and metabolic systems to stabilize to a new environment thereby minimizing risk of complications; this period also minimizes the effects of uncontrolled environmental influences on the results obtained from the experimental protocol.
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  • Animal stress - Investigators and research staff should be familiar with the normal behavior of the species and recognize abnormal behaviors. Since distress can alter experimental results, efforts should be targeted to reduce stresses associated with survival surgery, prolonged studies, confinement, and chronic pain.
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  • Proper handling and restraint - Proper handling and restraint will help prevent injury and minimize stress, to both the animal and personnel! Consultation with the veterinarian is advised.
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  • Antimicrobial prophylaxis - Antimicrobial agents might be indicated prophylactically for certain surgical procedures or when known breaks in sterility occur, but should not be used as a substitute for proper aseptic techniques. Please consult the veterinarian about using antimicrobials for each individual animal.
  • Survival Surgery - Surgery from which the subject regains consciousness from anesthesia for any period of time prior to a complete recovery, use, or euthanasia.


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