Dictyocaulus is a genus of nematode parasites of the bronchial tree of horses, sheep, goats, deer, and cattle.

Dictyocaulus 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.

Symptoms of D. viviparus can include coughing, rapid shallow breathing, expiratory dyspnea, tactile fremitus, serous nasal discharge, pyrexia, increased pulse rate, weight loss, and diarrhea.

Pasture management should take into consideration the infectiveness of these organisms since the larvae can survive in the soil for extended periods of time.

Donkeys usually show no disease and can be silent carriers (and shedders) of this parasite, which causes clinical signs in horses.