Abstract: Crenosoma vulpis and Eucoleus aerophilus are 2 important lung nematodes of wild and domestic carnivores. A recent report underscored the severity of bronchial gland hyperplasia and bronchiolar metaplasia in parasitized foxes. The objective of this study was to quantify the degree of bronchial gland hyperplasia and bronchiolar metaplasia in foxes naturally infected with C. vulpis and E. aerophilus. Fifty-one trapped wild foxes and 12 farmed foxes were necropsied and 6 lung sites were processed for histopathological examination. The degree of bronchial gland hyperplasia was evaluated using the Reid index (bronchial gland to bronchial wall ratio) and the severity of goblet cell metaplasia was determined by morphometric analyses. None of the farmed foxes had microscopic evidence of nematodes in the lung, whereas evidence of C. vulpis and E. aerophilus was detected in 66.6% (34/51) and 49% (25/51), respectively, of the wild foxes. Lungworms caused a significant increase in the Reid index with 2-fold increase in the size of bronchial glands. Bronchiolar goblet cell metaplasia was present in 60.7% (31/51) of foxes harboring C. vulpis and in 23.5% (12/51) of those with E. aerophilus. The odds ratio for bronchiolar goblet cell metaplasia was 16.0 (p<0.001) for C. vulpis and 9.0 (p<0.001) for E. aerophilus. It was concluded that the severity of airway inflammation and bronchiolar obstruction in foxes parasitized with C. vulpis and E. aerophilus is similar to that reported in humans with chronic obstructive pulmonary disease. The clinical significance of airway changes in apparently healthy wild foxes needs to be investigated.