Trachea and bronchi
Epidemiology: Metastrongyloid nematode of bronchi (dogs and other canids). Adult worms (males; 4 to 8 mm long, females; 12
to 16 mm long) parasitize the terminal bronchi of the respiratory tract where eggs are laid, develop and hatch, larvae then
coughed up and swallowed to be passed in the feces.
- Dogs infected when ingest gastropod (snails) intermediate hosts. Larvae migrate to the lungs by way of the visceral lymphatic
or via the hepatic portal system: prepatent period about 18 to 21 days.
Clinical signs: Infection occurs during summer in dogs living or visiting rural areas frequented by foxes, the more usual
definitive host. - dry, nonproductive cough easily elicited by tracheal palpation. Cough may be chronic and productive.
- Radiology: Diffuse bronchial patterns with prominent interstitial markings.
- Bronchoscopy: Moderate mucoid to mucopurulent discharge in the airways. Cytology of tracheal wash: reveal inflammatory cells,
mainly eosinophils (matching a peripheral eosinophilia).
Diagnosis: Larvae (pointed tail, 250 - 300 um) in feces or tracheal wash sample.
Treatment: Fenbendazole (50 mg/kg PO, q24h, 3 days, or 20 mg/kg, PO, q24h, 14 days).
- Levamisole (7.5 mg/kg, PO, once, followed by a second dose 2 days later).
Epidemiology: Metastrongyloid nematode: causing nodules in the terminal trachea and bronchi of dogs and other canids (coyotes,
foxes). Adult worms found in subepithelial fibrous nodules usually close to the bifurcation of the trachea and extending down
into the mainstem bronchi. Thin-shelled eggs or larva (L1 - infective stage and very similar to F. hirthi) are coughed up, swallowed, enter feces, or coat regurgitated food.
- Direct lifecycle. Pups infected by L1 in sputum (infected when cleaning, or coating regurgitated food.
Clinical signs: Dry cough (often precipitated by exercise or tracheal palpation) unresponsive to antibiotics or
- Severe respiratory distress due to upper airway obstructive disease.
Diagnosis: L1 in fecal samples or in transtracheal washes. Bronchoscopy: identifies the brown reddy nodules at the tracheal
bifurcation. Radiology may reveal soft tissue nodular densities at the tracheal bifurcation.
Treatment: Physical removal of nodules via bronchoscopy can be life saving.
- Oxfendazole (10 mg/kg PO, q24h, 28 days). Only drug known to work.
- Prednisone (0.5 - 1 mg/kg PO, q12h, 5 days post-nodule removal). Removes inflammation with worm death.
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