Smith H J
Can J Comp Med. 1974 Apr;38(2):139-44.
Fortnightly treatment of susceptible calves with 1-tetramisole during the first two months of continuous exposure to pastures residually heavily-infected with Ostertagia ostertagi, Cooperia oncophora and Nematodirus helvetianus did not prevent the development of clinical parasitic gastroenteritis, although the infections were not as severe as in nontreated calves. Development of resistance in treated calves was manifested by significantly smaller numbers of Cooperia eggs in utero (which were reflected by reduced fecal egg counts) and by significantly smaller Nematodirus worm burdens than in susceptible calves that commenced grazing coincident with cessation of treatment. The findings also indicated that resistance to Nematodirus helvetianus was slower in developing in treated than in nontreated infected calves.
在持续接触被奥斯特他线虫、牛古柏线虫和瑞士细颈线虫严重残留感染的牧场的头两个月，每两周用左旋咪唑对易感犊牛进行治疗，虽未能预防临床寄生性胃肠炎的发生，不过感染程度不像未治疗的犊牛那么严重。与治疗结束时开始放牧的易感犊牛相比，经治疗的犊牛产生耐药性的表现为子宫内牛古柏线虫卵数量显著减少（这反映在粪便虫卵计数降低上）以及牛细颈线虫虫体负荷显著降低。研究结果还表明，与未治疗的感染犊牛相比，经治疗的犊牛对瑞士细颈线虫产生耐药性的速度较慢。
