Dictyocaulus filaria

Dictyocaulus is a genus of nematode parasites of the bronchial tree of horses, sheep, goats, deer, and cattle. Dictyocaulus arnfieldi is the lungworm of horses, and Dictyocaulus viviparus is the lungworm affecting ruminants. D. viviparus is the most common lungworm of cattle; the infection is also known as husk or parasitic bronchitis. Although classified as the same parasite, some people believe that the D. viviparus of deer and elk should be reclassified as a different species, including D. eckertii in New Zealand. However, both species have been shown capable of cross-infecting cattle and cervids (at least in New Zealand) .