Lungworms are parasitic nematode worms of the order Strongylida that infest the lungs of vertebrates.
Different species are found in cattle and deer (D. viviparus), donkeys and horses (D. arnfeldi), and sheep and goats (D. filaria).
In the case of A. abstrusus the cat is normally infected by eating a bird or rodent that has itself eaten the original host.
The eggs or L1 larvae that reside in the lungs are coughed up and then ingested back into the stomach and released into the environment via the feces.
If an animal is suspected of lungworm infection, there are many ways to detect this parasitic infection such as performing one or more of the following techniques: a complete medical history including lung auscultation (stethoscope examination), doing a chest X ray, fecal examination for detection of ova or larvae, examination of respiratory secretions for ova or larvae, and/or a complete blood count (CBC) to check for signs of increase in eosinophils, While examination of feces is more commonly performed in cattle as a diagnostic, transtracheal wash cytology can occasionally yield lungworm eggs in infected animals.
Lungworms and other sheep parasites feature heavily in the 20th century novel Independent People (Sjálfstætt fólk) by Icelandic author Halldór Laxness.