Introduction

• Cause: infection with parasitic nematode.
• Signs: chronic, non-productive cough.
• Diagnosis: radiography, bronchoscopy, cytology.
• Treatment: anthelmintic.
• Prognosis: good, although severe infection may be difficult to resolve.
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Pathogenesis

Etiology

• Infection with Oslerus osleri Oslerus (Filaroides) osleri (formerly Filaroides osleri), a parasitic nematode worm.

Predisposing factors

General

• Densely stocked kennels, eg Greyhound kennels.

• Poor hygiene conditions.

Pathophysiology

• Direct transmission is suggested.
• Infection via feco-oral route, or regurgitated feeding → larvae pass via lymphatics to bronchial tree.
• Worms develop in nodules → eggs layed by female are coughed up and swallowed to pass out in feces.

• Infective larvae are ingested via contact with infected feces or contaminated environment.
• Infection commonly acquired by puppies <6 weeks old through contact with infected dam.
• Larvae penetrate intestine and migrate via lymphatics to lung.
• Migrate from alveolar tissue into tracheobronchial tree and travel to bifurcation of trachea where they continue development in granulomatous nodules.
• Nodules are completely encapsulated except for a small pore through which mature female lays eggs.
• The eggs immediately hatch to release infective larvae which are coughed up and swallowed by host to appear in feces.
• The nodules cause tracheobronchial irritation → chronic cough.

Timecourse

• Months. (Although signs often appear around 5-6 months, many animals are not presented for investigation until months later.)

Diagnosis

Treatment

Prevention

Outcomes