Samson J, Holmes J C, Jorgenson J T, Wishart W D
J Wildl Dis. 1987 Jul;23(3):396-403. doi: 10.7589/0090-3558-23.3.396.
Twelve free-ranging Rocky Mountain bighorn lambs (Ovis canadensis canadensis), each exposed experimentally to 125-1,000 infective third-stage larvae of Protostrongylus stilesi and P. rushi, shed significantly more first-stage larvae in their feces than did control lambs, but showed no clinical signs of illness and had equivalent summer and overwinter survival as control lambs. Two adult ewes, each exposed to 925 infective larvae, showed no increase in numbers of first-stage larvae in their feces; both survived at least 14 mo postexposure. Experimentally exposed lambs did not differ from control lambs in numbers of larvae in their feces in the following summer. Three experimental lambs had 313-402 adult P. stilesi and 0-97 adult P. rushi on necropsy; two control lambs had 255 and 270 P. stilesi and no P. rushi. The presence of these numbers of lungworms did not appear to be sufficient to precipitate lungworm pneumonia in bighorn lambs under the conditions of this study.
12只自由放养的落基山大角羊羔羊（加拿大盘羊指名亚种），每只都经实验暴露于125 - 1000条斯氏原圆线虫和鲁氏原圆线虫的感染性第三期幼虫，其粪便中排出的第一期幼虫明显多于对照羔羊，但未表现出疾病的临床症状，且夏季和越冬存活率与对照羔羊相当。2只成年母羊，每只暴露于925条感染性幼虫，其粪便中第一期幼虫数量未增加；两只母羊在暴露后至少存活了14个月。在接下来的夏天，经实验暴露的羔羊粪便中的幼虫数量与对照羔羊没有差异。3只实验羔羊在尸检时发现有313 - 402条斯氏原圆线虫成虫和0 - 97条鲁氏原圆线虫成虫；2只对照羔羊有255条和270条斯氏原圆线虫成虫，没有鲁氏原圆线虫成虫。在本研究条件下，这些数量的肺线虫似乎不足以在大角羊羔羊中引发肺线虫肺炎。
