Evidence of ivermectin resistance by Parascaris equorum on a Texas horse farm
Evidence of ivermectin resistance by Parascaris equorum on a Texas horse farm
复制标题
DOI：
10.1016/j.jevs.2006.12.002
复制
发表时间：
2007-02-01
影响因子：
1.3
通讯作者：
Thompson, J. A.
中科院分区：
文献类型：
--
作者：
Craig, T. M.;Diamond, P. L.;Thompson, J. A.
从 2 个月大开始，每两周收集一次粪便样本，对来自德克萨斯州一个农场的 32 匹小马驹进行了监测。在第一次收集时给马驹注射伊维菌素糊剂，然后每月注射一次。当伊维菌素治疗后 2 周，马驹的寄生虫卵计数高于治疗时，则按制造商推荐剂量 (6.6 mg/kg) 或在检测到绦虫卵时按推荐剂量的两倍 (13.2 mg/kg) 施用噻嘧啶双羟萘酸盐。伊维菌素治疗后 2 周，直到马驹 8 个月大时，观察到寄生虫卵计数增加或仅轻微减少（小于 75%），此时处理后粪便卵计数减少 85%。当噻嘧啶按制造商推荐的剂量给药时，虫卵计数减少了 42% 至 84%，但在 13.2 mg/kg 剂量下，治疗后 2 周粪便虫卵计数减少了 98% 至 100%。然而，即使在较高剂量下，噻嘧啶也无法控制圆线虫卵计数，而伊维菌素可将粪便圆线虫卵计数减少 99% 以上（治疗后 2 周测定）。噻嘧啶（而非伊维菌素）降低了寄生虫卵数量。伊维菌素（而非噻嘧啶）在给药后 2 周降低了圆线虫卵数量。单一药物适用于所有年龄段的马匹寄生虫控制方法需要重新思考。为了持续控制寄生虫，可能需要联合使用药物或更仔细地评估马驹的驱虫药。
By collecting fecal samples every 2 weeks beginning at 2 months of age, 32 foals from a single Texas farm were monitored. The foals were administered ivermectin paste at the time of the first collection and again monthly. When foals had Parascaris egg counts higher 2 weeks after ivermectin treatment than at treatment, they were administered pyrantel pamoate at the manufacturer's recommended dose (6.6 mg/kg) or at twice the recommended dose (13.2 mg/ kg) when tapeworm eggs were also detected. An elevation or only minimal reduction (less than 75%) in Parascaris egg counts was seen 2 weeks after ivermectin treatment until the foals were 8 months of age, at which time there was an 85% reduction in fecal egg count after treatment. When pyrantel was administered at the manufacturer's recommended dose, a 42% to 84% reduction in egg counts occurred, but at 13.2 mg/kg there was a 98% to 100% reduction in fecal egg counts 2 weeks posttreatment. However, pyrantel failed to control strongylate egg counts even at the elevated dose, whereas ivermectin reduced strongylate fecal egg counts by greater than 99%, determined 2 weeks posttreatment. Pyrantel, but not ivermectin, lowered Parascaris egg counts. Ivermectin, but not pyrantel, lowered strongyle egg counts 2 weeks post administration. A single drug for all ages of horses approach to parasite control requires rethinking. Combinations of drugs or more careful evaluation of anthelmintics in foals may be necessary for continued parasite control.