Smith M A, Nolan T J, Rieger R, Aceto H, Levine D G, Nolen-Walston R, Smith B I
Department of Clinical Studies, New Bolton Center, University of Pennsylvania, Kennett Square, PA, USA.
Department of Pathobiology, University of Pennsylvania, Philadelphia, PA, USA.
Vet Parasitol. 2015 Nov 30;214(1-2):139-43. doi: 10.1016/j.vetpar.2015.09.025. Epub 2015 Sep 30.
In the last decade there have been numerous reports of anthelmintic resistant cyathostomins in many parts of the world. The objective of the present study was to evaluate the efficacy of the commercially available anthelmintics against cyathostomin egg shedding in the Mid-Atlantic region of the United States. A total of 989 horses from 67 different farms located in southeastern Pennsylvania, northern Delaware, and northeastern Maryland were treated with fenbendazole, oxibendazole, pyrantel pamoate, ivermectin, or moxidectin at their recommended dosages. Fecal egg count reduction testing was used to determine the efficacy of each anthelmintic on those horses with fecal egg counts of ≥ 200 eggs per gram on the day of treatment (272 horses). Decreased efficacy (reduction of strongyle-type fecal egg counts by less than 90%) was found for fenbendazole, oxibendazole, and pyrantel pamoate, with only 6%, 21% and 43% of horses showing reductions of greater than 90%, respectively. The macrocyclic lactones showed high efficacy in all horses sampled in this study. The decreased anthelmintic efficacy detected in this study adds further evidence for the existence of resistant cyathostomins throughout much of the eastern United States. Findings from this study can be used to create a more sustainable approach for parasite control programs.
在过去十年里，世界许多地区都有大量关于抗驱虫药的杯环线虫的报道。本研究的目的是评估美国中大西洋地区市售驱虫药对杯环线虫排虫卵的效果。来自宾夕法尼亚州东南部、特拉华州北部和马里兰州东北部67个不同农场的989匹马，按照推荐剂量接受了芬苯达唑、奥昔苯达唑、吡喹酮、伊维菌素或莫西菌素的治疗。粪便虫卵计数减少试验用于确定每种驱虫药对治疗当天粪便虫卵计数≥每克200个虫卵的马匹（272匹马）的疗效。发现芬苯达唑、奥昔苯达唑和吡喹酮的疗效降低（圆线虫型粪便虫卵计数减少不到90%），分别只有6%、21%和43%的马匹显示减少超过90%。大环内酯类药物在本研究中采样的所有马匹中都显示出高效。本研究中检测到的驱虫药疗效降低，进一步证明了美国东部大部分地区存在抗驱虫药的杯环线虫。本研究结果可用于制定更可持续的寄生虫控制计划方法。
