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  • Protocol Review
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Response to Protocol Review Scenario: Protocol is acceptable

Lab Animal volume 44, pages 204–205 (2015)Cite this article

Hypothermia is a safe and effective method for anesthetizing rodents up to 7 d old1,2. Hypothermia provides both immobilization and mild analgesia when body temperature is reduced to 10–20 ºC (ref. 3). Newly born rat pups cannot maintain their body temperature and are functionally poikilothermic, with thermoregulatory ability developing only during the third week of life. Therefore, they are tolerant of low temperatures and can recover by re-warming, even from near 0 °C body temperature4. I believe this information is key to this scenario. Hypothermia will be acceptable for anesthesia for as long as rat pups remain functionally poikilothermic (until 21 d of age). To reduce possible unintended pain associated with cooling, the technique for inducing hypothermia should include partial insulation of the pup (e.g., wrapping it in a latex blanket or aluminum foil). Aluminum foil can be placed on crushed ice and molded to form a groove wide enough to accommodate a single pup, thus maximizing its exposure to low temperature. Pups could be placed in the groove in a row, avoiding body contact, the start time recorded and their surface body temperature recorded every minute using a thermocouple probe4.

Opioid drugs provide effective analgesia against thermal, inflammatory and mechanical pain in neonatal rodents as young as 1 d of age and should be considered for use whenever analgesia would be provided for an adult animal1. Morphine targets the nociceptive pathway during transduction, modulation and perception, whereas hypothermia targets perception as a general anesthetic1,5. Therefore, Jeffries' plan to administer a single injection of morphine prior to the traumatic insult without any additional analgesia in combination with hypothermia should be acceptable.

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References

  1. National Research Council. Guidelines for the Care and Use of Mammals in Neuroscience and Behavioral Research (National Academies Press, Washington, DC, 2003).

  2. Gaertner, D.J., Hallman, T.M., Hankenson, F.C. & Batchelder, M.A. in Anesthesia and Analgesia in Laboratory Animals 2nd edn. (Academic, London, 2008).

    Google Scholar 

  3. Phifer, C.B. & Terry, L.M. Use of hypothermia for general anesthesia in preweanling rodents. Physiol. Behav. 38, 887–890 (1986).

    Article  CAS  Google Scholar 

  4. Janus, C. & Golde, T. The effect of brief neonatal cryoanesthesia on physical development and adult cognitive function in mice. Behav. Brain Res. 259, 253–260 (2014).

    Article  Google Scholar 

  5. Barr, G.A. Antinociceptive effects of locally administered morphine in infant rats. Pain 81, 155–161 (1999).

    Article  CAS  Google Scholar 

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  1. Goldberg is Director at Large & Executive Secretary, International Veterinary Academy of Pain Management, Boynton Beach, FL.,

    Mary Ellen Goldberg

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  1. Mary Ellen Goldberg
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Goldberg, M. Response to Protocol Review Scenario: Protocol is acceptable. Lab Anim 44, 204–205 (2015). https://doi.org/10.1038/laban.784

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