The life history of Filaroides osleri in wild and domestic canids in Australia

Abstract

Nodules containing Filaroides osleri were found in the tracheae and major bronchi of 41.2% of 340 dingo/wild dogs and in two of 13 foxes in Australia. Young dingoes, dingo-domestic dog crosses, labrador dogs and a fox were experimentally infected using first-stage larvae, some hatched others unhatched, recovered from the tracheae of infected animals and fed per os. Dingo-domestic dog crosses 30 weeks of age and older, as well as young kittens, were refractory to experimental infection. Second-stage larvae were found in the wall of the duodenum 4 days after infection (DAI), fourth-stage larvae in lung parenchyma and alveoli 14 DAI and immature, fifth-stage nematodes in the same site 34 DAI. Adult worms were in the definitive site in the trachea, near its bifurcation, 70DAI. Gravid female worms were recovered from this site 18 weeks after infection (WAI). Direct transmission of F. osleri occurred from an experimentally infected bitch to her pup approximately 8–10 weeks after parturition. It is postulated that transmission of this lungworm in wild Canidae occurs directly from parents to offspring during the period of regurgitative feeding of young at the time of weaning. This mode of transmission may be responsible for the rare occurrence of F. osleri in domestic dogs in Australia. First-stage larvae passed in the faeces are believed to play no significant role in transmission.