Yazwinski T A, Featherston H, Tucker C, Johnson Z
Department of Animal Sciences, University of Arkansas, Fayetteville 72701.
Am J Vet Res. 1994 Oct;55(10):1416-20.
We assessed the duration of ivermectin persistence by measuring posttreatment nematocidal effectiveness; topical and injectable formulations of ivermectin were evaluated. Thirty-five nematode-free calves were randomly allocated to 1 of 5 treatment groups (7 calves/group). The treatment (Trt) group designations were: Trt 1, nonmedicated; Trt 2, injectable ivermectin administered at the rate of 0.2 mg/kg of body weight on day 0; Trt 3, injectable ivermectin administered at the aforementioned rate, but on day 7; Trt 4, topically administered ivermectin at the rate of 0.5 mg/kg on day 0; and Trt 5, topically administered ivermectin at the aforementioned rate, but on day 7. All calves were subsequently given infective larvae of Haemonchus, Cooperia, Trichostrongylus, and Oesophagostomum spp on day 21. One week later, each calf was additionally administered infective larvae of Dictyocaulus and Ostertagia spp. Trial calves were euthanatized on trial days 49 to 52 for nematode quantitation. On the basis of geometric mean comparisons, total nematode burdens were reduced from control group counts by 98.9 and 86.3% for calves treated on days 7 and 0 with injectable formulations, respectively, and 97.2 and 64.7% for calves treated on days 7 and 0 with pour-on formulations, respectively. Trichostrongylus colubriformis infections were most refractory to the persistent activity of ivermectin, with H placei also proving to be persistence limiting. All treatments were easily administered, and adverse behavioral or tissue reactions were not observed.
我们通过测量治疗后杀线虫效果来评估伊维菌素的持续时间；对伊维菌素的局部和注射剂型进行了评估。35头无线虫犊牛被随机分配到5个治疗组中的1组（每组7头犊牛）。治疗（Trt）组的指定如下：Trt 1，未用药；Trt 2，在第0天以0.2 mg/kg体重的剂量注射伊维菌素；Trt 3，以上述剂量注射伊维菌素，但在第7天；Trt 4，在第0天以0.5 mg/kg的剂量局部施用伊维菌素；Trt 5，以上述剂量局部施用伊维菌素，但在第7天。随后在第21天给所有犊牛接种血矛线虫、库珀线虫、毛圆线虫和食道口线虫属的感染性幼虫。一周后，给每头犊牛额外接种网尾线虫属和奥斯特他线虫属的感染性幼虫。试验犊牛在试验第49至52天被安乐死以进行线虫定量。基于几何平均数比较，对于在第7天和第0天用注射剂型治疗的犊牛，线虫总负担分别比对照组计数减少了98.9%和86.3%，对于在第7天和第0天用浇泼剂型治疗的犊牛，分别减少了97.2%和64.7%。蛇形毛圆线虫感染对伊维菌素的持续活性最具抗性，H. placei也被证明是限制持久性的因素。所有治疗都易于实施，未观察到不良行为或组织反应。
