Hot-iron disbudding results in painful burn wounds that take weeks to heal. Spontaneous behaviors indicative of pain are apparent in the immediate hours after disbudding, but whether they occur later in the healing process is unknown. To evaluate whether ongoing pain was present around the time the necrotic tissue loosens from the scalp, we tested the effect of administration of local anesthetic 11 d after the procedure. Disbudded female Holstein and Jersey calves (n = 24) were randomly assigned to receive an injection of local anesthetic (lidocaine) or saline at the cornual nerve on both sides of the head. We recorded the frequency of 8 behaviors for 75 min: head shakes, head rubs, head scratches, ear flicks, tail flicks, bucks/jumps/kicks, grooming, and transitions between standing and lying. Calves treated with lidocaine shook their heads less and tended to flick their ears less than calves administered saline, consistent with the effects of pain relief previously reported in the immediate hours after disbudding. These calves also rubbed their head against the sides of the pen more often, suggesting lidocaine suppressed wound protective behavior. Head shaking and head scratching became more common in the last 25 min compared with the first 50 min in calves treated with lidocaine, consistent with the return of sensation to the disbudding wounds. No treatment differences in the other behaviors were observed. These results suggest that calves experience ongoing pain 11 d after hot-iron disbudding, adding to a growing body of evidence that pain persists for weeks after the procedure.

热铁喷出会导致灼伤，需要数周才能治愈。出汗后的几小时内就明显表现出自发的疼痛症状，但在康复过程的后期是否会发生，尚不清楚。为了评估坏死组织从头皮松动时是否存在持续的疼痛，我们在手术后11天测试了局麻药的作用。随机分配失足的雌性荷斯坦犊牛和泽西犊牛（n = 24），在头两侧的角神经处注射局部麻醉药（利多卡因）或生理盐水。我们记录了75分钟内8种行为的频率：摇头，擦头，抓头，甩耳，甩尾，大块/跳/踢，梳理以及站立和躺着之间的过渡。用利多卡因治疗的小牛比用生理盐水的小牛少摇头，也较不易甩动耳朵，这与先前报道的在缓解后数小时内缓解疼痛的效果一致。这些小牛还经常将头抵着笔的侧面摩擦，这表明利多卡因抑制了伤口的保护行为。与使用利多卡因治疗的小腿的前50分钟相比，最近25分钟的头摇和头部抓挠更为常见，这与感觉恢复到弥漫性伤口有关。在其他行为上未观察到治疗差异。这些结果表明，犊牛在热铁喷出后11 d会经历持续的疼痛，这增加了越来越多的证据表明疼痛持续了数周。