The final host of Aelurostrongylus abstrusus is cats. The male measures 7.5 mm and the female 9.9 mm. Males have a short bursa and the vulva of the female opens near the posterior end. Adult female worms lay their eggs in the alveoli of the cat's lung. The eggs hatch and the first stage larvae (L1) are carried up the trachea, swallowed and pass out with the feces.
The L1 can live for about 2 weeks in the environment. If the L1 find a snail or slug they enter the "foot" where they grow to the infectious third-stage (L3). If a paratenic host eats the snail, the L3 migrate into the tissues of the new host and arrest.
