Filaroides osleri

FILAROIDES (= Oslerus) 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.

Filaroides Infections

• 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.

• = Oslerus osleri
• Colonise the trachea of dogs
• Larva and adults accumulate in submucosal nodules of up to 1cm diameter at the tracheal bifurcation.
• Minimal inflammatory host reaction to the nematodes when they are alive - the size of the nodule is related to the number and size of the nematodes within it.
• When the parasites die, an intense foreign body reaction develops
• Tracheal nodules can cause coughing, usually in young dogs <18 months old.
• Severe infestation can cause significant occlusion of the airway.
• Uncommon, but sometimes seen in coughing greyhounds