BACKGROUND Epidural administration of morphine has been shown to be an effective analgesic strategy in horses; however, the possible occurrence of side effects limits its usage. In order to decrease their frequency, it is important to target the minimal effective plasma concentration and avoid overdosing. As to date species-specific pharmacokinetics data are not available for epidural morphine, the dosing regimen is usually established on the basis of clinical reports and personal experience. In certain physiological conditions, like gestation, the outcome of an empirical dosing scheme can be unpredictable. The aim of this case report is to describe the pharmacological profile of morphine and its metabolites after prolonged epidural administration in a pregnant mare and her foal. CASE PRESENTATION A 20 years old pregnant mare was presented to our hospital because of severe lameness, 2 months before delivery. Following an ineffective systemic pain treatment, an epidural catheter was inserted and morphine administered (initial dose 0.1 mg/kg every 8 h). Due to its efficacy in controlling pain, it was continued until end of gestation. Plasmatic concentration of morphine and its metabolites were assessed in the mare 6 weeks after starting the treatment, and in both the mare and foal during the first days after delivery. Plasmatic values similar to those previously reported in the literature following morphine short term administration through various routes and not accompanied by side effects were found in the mare, except during an excitatory period. Moreover, no evidence of dangerous drug accumulation or significant milk passage was noticed in the foal. Mild reduction of feces production with no signs of colic and two self-limiting episodes of excitement occurred during treatment in the mare. No side effects occurred during gestation and first phases of life in the foal. CONCLUSION Prolonged epidural administration of morphine in a pregnant mare allowed good pain control in absence of clinically relevant side effects, in both the mare and her foal. Sudden increase in morphine plasmatic concentration can occur and side effects appear; careful treatment to the lowest effective dose and continuous monitoring of the clinical condition of the treated horse should be performed.

中文翻译：

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长期硬膜外给药后，怀孕母马及其驹中的吗啡血浆浓度。

背景技术吗啡硬膜外给药已被证明是一种有效的镇痛策略。但是，可能发生的副作用限制了它的使用。为了降低它们的频率，重要的是将最小有效血浆浓度作为目标并避免剂量过量。迄今为止，对于硬膜外吗啡尚无物种特异性的药代动力学数据，通常根据临床报告和个人经验确定给药方案。在某些生理条件下，例如妊娠，经验性给药方案的结果可能无法预测。该病例报告的目的是描述在硬皮硬膜外长期服用妊娠母马和小马驹后，吗啡及其代谢产物的药理作用。病例介绍由于严重la行，在分娩前2个月将20岁的母马送至我们医院。在无效的全身性疼痛治疗后，插入硬膜外导管并给予吗啡（初始剂量每8小时0.1 mg / kg）。由于其控制疼痛的功效，一直持续到妊娠结束。开始治疗后6周，在母马中评估吗啡及其代谢产物的血浆浓度，分娩后头几天在母马和小马中评估其浓度。在母马中发现吗啡通过各种途径短期给药后的血浆值与文献中先前报道的相似，并且没有伴随副作用，但在兴奋期除外。此外，小马驹没有发现危险的药物蓄积或大量牛奶通过的迹象。在母马的治疗过程中，粪便的分泌物轻度减少，没有绞痛的迹象，并且出现了两次自我限制的兴奋发作。小马驹在妊娠和生命的最初阶段没有发生副作用。结论在母马和小马中，硬膜外给予吗啡可在没有临床相关副作用的情况下良好地控制疼痛。吗啡血浆浓度可能突然升高，并出现副作用。应当对最低有效剂量进行仔细治疗，并持续监测所治疗马匹的临床状况。在母马的治疗过程中，粪便的分泌物轻度减少，没有绞痛的迹象，并且出现了两次自我限制的兴奋发作。小马驹在妊娠和生命的最初阶段没有发生副作用。结论在母马和小马中，硬膜外给予吗啡可在没有临床相关副作用的情况下良好地控制疼痛。吗啡血浆浓度可能突然升高，并出现副作用。应当对最低有效剂量进行仔细治疗，并持续监测所治疗马匹的临床状况。在母马的治疗过程中，粪便产生轻度减少，没有绞痛的迹象，并且出现了两次自我限制的兴奋发作。小马驹在妊娠和生命的最初阶段没有发生副作用。结论在母马和小马中，硬膜外给予吗啡可在没有临床相关副作用的情况下良好地控制疼痛。吗啡血浆浓度可能突然升高，并出现副作用。应当对最低有效剂量进行仔细治疗，并持续监测所治疗马匹的临床状况。结论在母马和小马中，硬膜外给予吗啡可在没有临床相关副作用的情况下良好地控制疼痛。吗啡血浆浓度可能突然升高，并出现副作用。应当对最低有效剂量进行仔细治疗，并持续监测所治疗马匹的临床状况。结论在母马和小马中，硬膜外给予吗啡可在没有临床相关副作用的情况下良好地控制疼痛。吗啡血浆浓度可能突然升高，并出现副作用。应当对最低有效剂量进行仔细治疗，并持续监测所治疗马匹的临床状况。