Assessment of carprofen and buprenorphine on recovery of mice after surgical removal of the mammary fat pad

Abstract

The purpose of this study was to determine the level of pain elicited by mammary fat pad removal surgery and the effects of postoperative analgesics on recovery. Female FVB mice were anesthetized, and mammary fat pad removal was performed. After surgery, mice received carprofen, buprenorphine, a combination of carprofen and buprenorphine, or saline treatment. Additional mice received anesthesia but no surgery or treatment. Food and water intake, body weight, wheel running activity, and a visual assessment score were recorded daily for 4 d after surgery and compared with presurgical findings. Corticosterone metabolites in fecal samples were analyzed at 12 and 24 h postsurgically and compared with baseline values. All surgical groups had significantly decreased food intake at 24 h, with a return to baseline by 48 h. The combination treatment resulted in a significantly decreased water intake and body weight at 24 h. All surgical groups had significantly decreased wheel running activity at 24 h only. The visual assessment scores indicated mild pain for all surgical groups, with the buprenorphine treated mice showing the highest pain index scores, as compared with nonsurgical controls. Fecal corticosterone metabolite levels did not differ significantly between any of the groups or across time. The parameters used in this study did not indicate that administration of these analgesic regimens improved recovery as compared with that of saline-treated mice. Care should be taken when using visual assessment scores to evaluate pain in mice, given that analgesics may have side effects that inadvertently elevate the score.

Figure 1.

Visual assessment scoring system. Each characteristic was scored independently and then added together to obtain the final pain index score for each mouse at each time point. This scoring system was modified slightly from a previously published visual assessment score for mice. Changes from the published scoring system are indicated with *.

Figure 2.

Postoperative changes in food intake. Baseline values are represented as 1.0, and subsequent values are given as a change relative to baseline values. Each point represents the mean ± SE. *, P < 0.01 compared with value for nonsurgical control group at the same time point. †, P < 0.03 compared with baseline.

Figure 3.

Postoperative changes in water intake. Baseline values are represented as 1.0, and subsequent values are given as a change relative to baseline values. Each point represents mean ± SE. †, P = 0.003 compared with baseline value.

Figure 4.

Postoperative changes in body weight. Baseline values are represented as 1.0, and subsequent values are given as a change relative to baseline values. Each point represents mean ± SE. *, P = 0.003 compared with value for nonsurgical control group at the same time point; †, P ≤ 0.045 compared with baseline.

Figure 5.

Postoperative changes in voluntary wheel running activity. Baseline values are given as 1.0, and subsequent values are given as a change relative to baseline values. Each point represents the mean ± SE. *, P < 0.02 compared with values from all other groups at the same time point.

Figure 6.

Postoperative pain index scores in female FVB mice. The maximum pain index score possible was 13. Values are given as the mean pain index score ± SE. All surgical groups were significantly (P < 0.02) different from baseline at all time points. *, P < 0.05 compared with value from the nonsurgical control group at the same time point.