Dictyocaulus filaria

Dictyocaulus filaria occurs in sheep in many areas of the world, including Canada, where it seems to be a rare cause of clinical disease. The life cycle and general biology of D. filaria is similar to that for D. viviparus, although details of its pathophysiology have not been so extensively studied. In Canada, oral and injectable ivermectin (VARIOUS) are approved for the treatment of D. filaria.

Muellerius capillaris
Protostrongylus rufescens
Cystocaulus ocreatus

These are protostrongylid lungworms and infect sheep (and goats) most commonly in warmer, damper regions of the world. Adult M. capillaris and C. ocreatuslive in the lung parenchyma, and adult P. rufescens in the smaller bronchi and bronchioles. First-stage larvae (those of M. capillaris have a dorsal spine) are passed in the feces. Protostrongylids require a gastropod intermediate host in which the infective larvae develop. Infection of the mammalian host is by ingestion of infected gastropods or of infective larvae that have emerged spontaneously from the gastropods. M. capillaris has been reported from sheep and goats in Canada, but seems rarely to be clinically significant.

None of the lungworms of sheep or goats are known to be zoonotic.