Filaroides osleri

F. osleri is atypical of the Metastrongyloidea in almost every way.
Adults (approximately 1cm) are found in dogs clustered in fibrous nodules (few mm - 2cm) on tracheal wall (near bifurcation of trachea).
This means that small numbers of L1 are found in the sputum, and can either be passed to the skin during grooming, or can be passed in the faeces (dead-end for life-cycle).
Transmission from bitch to pups occurs during grooming via transfer of sputum.
Horizontal transmission rarely, if ever, happens.
Infection is usually asymptomatic, but if symptoms are present, there is a chronic, dry, debilitating cough - performance of greyhounds may be affected.

F. osleri is usually associated with particular boarding kennels.
Diagnosis and treatment are difficult.
The Baermann apparatus is used to recover L1 from faeces.
Larvae are, however, few in number and have sluggish movements.
They may, therefore, be very difficult to demonstrate in faeces or sputum.
Endoscopy (to visualise the tracheal nodules) is often required to confirm diagnosis.

Fenbendazole is licensed for the treatment.