Abstract
Aelurostrongylus abstrusus caused focal interstitial pneumonia during the first 25 days after infection. Although the prepatent period of A. abstrusus is 42 d the adult worms lay eggs in the pulmonary parenchyma as early as 25 d after infection. These eggs become centres of extensive granulomata. Adult worms elicit focal interstitial pneumonia, bronchiolitis, and a variety of pulmonary arterial changes.