Using the Mouse Grimace Scale to reevaluate the efficacy of postoperative analgesics in laboratory mice.

Postoperative pain management in animals is complicated greatly by the inability to recognize pain. As a result, the choice of analgesics and their doses has been based on extrapolation from greatly differing pain models or the use of measures with unclear relevance to pain. We recently developed the Mouse Grimace Scale (MGS), a facial-expression-based pain coding system adapted directly from scales used in nonverbal human populations. The MGS has shown to be a reliable, highly accurate measure of spontaneous pain of moderate duration, and therefore is particularly useful in the quantification of postoperative pain. In the present study, we quantified the relative intensity and duration of postoperative pain after a sham ventral ovariectomy (laparotomy) in outbred mice. In addition, we compiled dose-response data for 4 commonly used analgesics: buprenorphine, carprofen, ketoprofen, and acetaminophen. We found that postoperative pain in mice, as defined by facial grimacing, lasts for 36 to 48 h, and appears to show relative exacerbation during the early dark (active) photophase. We find that buprenorphine was highly effective in inhibiting postoperative pain-induced facial grimacing in mice at doses equal to or lower than current recommendations, that carprofen and ketoprofen are effective only at doses markedly higher than those currently recommended, and that acetaminophen was ineffective at any dose used. We suggest the revision of practices for postoperative pain management in mice in light of these findings.

An outbreak of Pasteurella pneumotropica in genetically modified mice: treatment and elimination.

A closed breeding colony comprising genetically engineered, wild-type, and stock mice presented with varying degrees of bilateral mucopurulent conjunctivitis and panophthalmitis. The one mouse with unilateral corneal ulceration, a knockout animal, was submitted for necropsy, and bacterial culture samples were obtained from the affected eye and uterus. In addition, ocular swabs from another 12 clinically affected animals, consisting of knockout, transgenic, wild-type, and stock mice, were submitted for bacterial culture analysis. All samples revealed pure cultures of Pasteurella pneumotropica. At the time of the outbreak, there were approximately 600 mice in the affected colony, with the majority of clinical cases (58 of 79) involving knockout mice and the remainder (21 of 79) in the other strains. Treatment consisted of enrofloxacin in the drinking water at 85 mg/kg daily for 14 days. Within 7 days of initiation of treatment, all existing clinical cases had resolved and no new clinical cases developed. Four weeks after completion of treatment, two groups of mice were submitted for multiple organ bacteriological analyses. One group of mice represented those animals which had complete resolution of clinical signs, and the second group of mice represented those individuals which had remained asymptomatic throughout the outbreak. All post treatment bacterial culture samples were negative for Pasteurella pneumotropica. By using the oral enrofloxacin suspension in the drinking water rather than the parenteral counterpart, concerns regarding the pharmacokinetics, specifically drug bioavailability via the oral route, problems with aqueous immiscibility and drug degradation within an aqueous medium were not potentially confounding variables. The clinical management, ease of administration, and efficacy of using an oral antibiotic formulation for the treatment and eradication of Pasteurella pneumotropica from a large mouse colony are presented in this paper.