Gogolewski R P, Allerton G R, Pitt S R, Thompson D R, Langholff W K, Hair J A, Fulton R K, Eagleson J S
Merck Research Laboratories, Ingleburn N.S.W., Australia.
Vet Parasitol. 1997 Apr;69(1-2):95-102. doi: 10.1016/s0304-4017(96)01095-3.
A series of five controlled studies involving 114 cattle were conducted in Australia, North America and the United Kingdom to examine the effect of simulated rain, coat length and exposure to natural climatic conditions, on the efficacy of a topical formulation of eprinomectin against nematode parasites of cattle. In all trials infections were induced with a range of bovine nematode species and treatment was applied when the majority of nematodes were mature. In one study, simulated rain was applied to cattle ending one hour before treatment or beginning one, three or six hours after treatment. In a second study cattle had short (1 cm) or long (3-6 cm) haircoats at the time of treatment. Three other studies were conducted using cattle housed indoors or exposed to various natural climatic conditions. Nematode counts were determined using standard techniques and the efficacy of treatment was assessed relative to vehicle-treated controls. Regardless of the timing of simulated rain relative to treatment, eprinomectin was at least 99.9% effective (P < 0.01) against Haemonchus placei, Ostertagia ostertagi. Trichostrongylus axei and Cooperia spp. There were also no differences (p > 0.10) in efficacy between treatment administered to dry or wet cattle, or treatment administered before or after simulated rainfall. Efficacies against O. ostertagi, T. axei, Cooperia ancophora and Dictyocaulus viviparus were > 99.5% (p < 0.01) regardless of the length of the haircoat at the application site. Exposure of treated cattle to sunshine and precipitation had no effect on anthelmintic efficacy (p > 0.10) with efficacies of greater than 99.5% being maintained against H. placei, O. ostertagi (adult and fourth-stage larvae), T. axei, Cooperia spp., Nematodirus helvetianus (adult and inhibited fourth-stage larvae) and Oesophagostomum radiatum. These findings indicate that eprinomectin (500 micrograms/kg) in a topical formulation is a safe and highly effective nematocide for cattle regardless of their coat length and this high level of efficacy is maintained in cattle exposed to a wide variety of climatic conditions.
在澳大利亚、北美和英国开展了一系列五项对照研究，涉及114头牛，以考察模拟降雨、被毛长度以及自然气候条件对依普菌素局部制剂防治牛线虫寄生虫效果的影响。在所有试验中，用多种牛线虫种类诱发感染，并在大多数线虫成熟时进行治疗。在一项研究中，在治疗前一小时结束或治疗后一、三或六小时开始对牛进行模拟降雨。在第二项研究中，治疗时牛的被毛短（1厘米）或长（3 - 6厘米）。另外三项研究使用室内饲养的牛或暴露于各种自然气候条件下的牛进行。使用标准技术确定线虫数量，并相对于赋形剂处理的对照评估治疗效果。无论模拟降雨相对于治疗的时间如何，依普菌素对牛血矛线虫、奥氏奥斯特线虫、艾氏毛圆线虫和古柏属线虫的有效性至少为99.9%（P < 0.01）。对干燥或潮湿的牛进行治疗，或在模拟降雨之前或之后进行治疗，在效果上也没有差异（p > 0.10）。无论施用部位被毛长度如何，对奥氏奥斯特线虫、艾氏毛圆线虫、安氏古柏线虫和胎生网尾线虫的有效性均> 99.5%（p < 0.01）。接受治疗的牛暴露于阳光和降雨对驱虫效果没有影响（p > 0.10），对牛血矛线虫、奥氏奥斯特线虫（成虫和第四期幼虫）、艾氏毛圆线虫、古柏属线虫、瑞士细颈线虫（成虫和抑制性第四期幼虫）和辐射食道口线虫的有效性保持在99.5%以上。这些发现表明，局部制剂中的依普菌素（500微克/千克）对牛而言是一种安全且高效的杀线虫剂，无论其被毛长度如何，并且在暴露于各种气候条件下的牛中都能保持这种高水平的有效性。
