in the animal-use protocol and approved by the IACUC. In addition, traditional tracer injections, lesions, or recording may require that the surgical procedure be conducted outside facilities dedicated for aseptic surgery (such as in a laboratory setting). This represents a deviation from the Guide and the AWRs, so approval for such procedures rests with the IACUC. Performance standards and a team approach by the IACUC, the veterinarian, and the investigator can ensure that the spirit of the regulation is met and that veterinary care will not be compromised as a result of surgical procedures conducted under non-aseptic conditions (see “Asepsis and Physical Environment” in Chapter 3 and “Modified Surgical Settings” in Chapter 4).

EUTHANASIA

Laboratory animals can be euthanized in three ways: hypoxia, depression of neural activity necessary for life function, and physical disruption of brain activity and destruction of neurons necessary for life (Balaban and Hampshire, 2001). However, the physiology of the perinatal animal renders some of the euthanasia methods used for adult animals inadequate and therefore inadvisable for perinatal animals (NRC, 1996).

In rodent fetuses that are less than E14, the lack of neural development prevents signs of fetal response to noxious stimuli, so euthanasia of the dam or removal of the fetus from the dam will result in the painless death of the fetus without a requirement for additional measures (NIH, 1997).

Inhalant agents, including inhalant anesthetics and CO2, that cause death by cerebral depression and/or hypoxia, must be used carefully for euthanasia of older fetuses or neonates. The comparatively hypoxic intrauterine environment renders these young animals much more tolerant of hypoxic conditions than adults (Singer, 1999), and euthanasia with an agent that causes death by hypoxia, such as CO2, may take 30 minutes or longer. Therefore, if these agents are used, personnel should be appropriately trained to use prolonged exposure times. Ideally, death should be verified by a secondary method such as decapitation or cervical dislocation.

Older fetuses and neonates can also be euthanized with chemical anesthetics, decapitation, or cervical dislocation. If chemical fixation of the whole fetus is necessary, the fetus should be properly anesthetized before fixation (NIH, 1997). In accordance with the report of the AVMA Panel on Euthanasia (2001), some physical methods of euthanasia, such as decapitation, require appropriate training, experience, and specific approval by the IACUC.



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