Most research laboratories abide by guidelines and mandates set by their research institution regarding the administration of
analgesics to control
pain during the postoperative period. Unfortunately, measuring
pain originating from the head is difficult, making adequate decisions regarding
pain control following stereotaxic surgery problematic. In addition, most postsurgical
analgesia protocols require multiple
injections over several days, which may cause stress and distress during a critical recovery period. Here we sought to (1) assess the degree of
postoperative pain following
craniotomy in mice, (2) compare the efficacy of three common rodent
analgesics (
carprofen,
meloxicam and
buprenorphine) for reducing this
pain and (3) determine whether the route of administration (injected or self-administered through the drinking supply) influenced
pain relief post-
craniotomy. Using the mouse grimace scale (MGS), we found that
injectable analgesics were significantly more effective at relieving post-
craniotomy pain, however, both routes of administration decreased
pain scores in the first 24 h postsurgery. Specifically,
buprenorphine administered independently of administration route was the most effective at reducing MGS scores, however, female mice showed greater sensitivity to
carprofen when administered through the water supply. Although it is necessary to provide laboratory animals with
analgesics after an invasive procedure, there remains a gap in the literature regarding the degree of
craniotomy-related
pain in rodents and the efficacy of alternative routes of administration. Our study highlights the limitations of administering drugs through the drinking supply, even at doses that are considered to be higher than those currently recommended by most research institutions for treating
pain of mild to moderate severity.