Guide for the Care and Use of Laboratory Animals - Office of ...

122 GUIdE FOR ThE CARE ANd USE OF LAbORATORy ANIMALSAlleviation of chronic pain may be more challenging than postproceduralpain; commercially available opiate slow-release transdermal patchesor implantable analgesic-containing osmotic minipumps may be useful forsuch relief. Because of wide individual variation in response to analgesics,regardless of the initial plan for pain relief, animals should be closely monitoredduring and after painful procedures and should receive additionaldrugs, as needed, to ensure appropriate analgesic management (Karas et al.2008; Paul-Murphy et al. 2004). Nonpharmacologic control of pain maybe effective and should not be overlooked as an element of postproceduralor perioperative care for research animals (NRC 2009a; Spinelli 1990).Appropriate nursing support may include a quiet, darkened recovery orresting place, timely wound or bandage maintenance, increased ambientwarmth and a soft resting surface, rehydration with oral or parenteral fluids,and a return to normal feeding through the use of highly palatable foodsor treats.Most anesthetics cause a dose-dependent depression of physiologichomeostasis and the changes can vary considerably with different agents.The level of consciousness, degree of antinociception (lack of responseto noxious stimuli), and status of the cardiovascular, respiratory, musculoskeletal,and thermoregulatory systems should all be used to assess theadequacy of the anesthetic regimen. Interpretation and appropriate responseto the various parameters measured require training and experience with theanesthetic regimen and the species. Loss of consciousness occurs at a lightplane of anesthesia, before antinociception, and is sufficient for purposes ofrestraint or minor, less invasive procedures, but painful stimuli can induce areturn to consciousness. Antinociception occurs at a surgical plane of anesthesiaand must be ascertained before surgery. Individual animal responsesvary widely and a single physiologic or nociceptive reflex response may notbe adequate for assessing the surgical plane or level of analgesia (Masonand Brown 1997).For anesthesia delivery, precision vaporizers and monitoring equipment(e.g., pulse oximeter for determining arterial blood oxygen saturation levels)increase the safety and choices of anesthetic agents for use in rodents andother small species. For injectable anesthestic protocols, specific reversalagents can minimize the incidence of some side effects related to prolongedrecovery and recumbency. Guidelines for the selection and proper useof analgesic and anesthetic drugs should be developed and periodicallyreviewed and updated as standards and techniques are refined. Agents thatprovide anesthesia and analgesia must be used before their expiration datesand should be acquired, stored, their use recorded, and disposed of legallyand safely.Some classes of drugs such as sedatives, anxiolytics, and neuromuscularblocking agents may not provide analgesia but may be useful when