Unilateral plantar incision induces short-lasting guarding behavior but no reduction in crossings of a noxious surface during the operant mechanical conflict (MC) test. (A) Enhancement of mean guarding scores for the injured hindpaw after deep (skin plus muscle) incision or skin incision alone. The guarding score is normalized by subtracting the score of the uninjured hindpaw in each animal. Two-way ANOVA followed by Bonferroni multiple comparison tests: treatment, F(2,79) = 51.5, P < 0.0001; test, F(2,79) = 14.0, P < 0.0001; asterisks indicate differences compared to pretests on day 0. (B) Lack of effects of unilateral plantar incision on the mean number of crossings of noxious 4-mm probes during 5-minute MC test. Two-way ANOVA followed by Bonferroni tests: test x treatment, F(5,70) = 1.82, P = 0.02; test, F(5.74,132) = 20, P < 0.0001; treatment, F(1,23) = 4.16, P = 0.557. (C) The same data, showing only the crossings of the 4-mm probes. Red arrow indicates the time of incision in each panel.