Feline Lungworm

This was a young cat with a history of coughing, eventually leading to respiratory distress and death.

Fig 1. Histopathology. Low magnification of the lung, effaced by largely granulomatous inflammation. Bottom right – embryonated parasite eggs; bottom left – few thin nematode larvae; top right – bronchus filled with neutrophils. H&E x40 magnification.
Fig 2. Higher magnification view of parasite larvae and eggs within the granulomatous to pyogranulomatous inflammation. H&E x100 magnification.

Final Diagnosis

Severe suppurative to pyogranulomatous and eosinophilic bronchopneumonia with large numbers of intralesional parasitic larvae and ova


This is consistent with feline lungworm (Aelurostrongylus abstrusus) disease. Although the prepatent period of this parasite is approximately 4 - 6 weeks, pulmonary lesions may be evident much earlier and in one study, ova and larvae were identified together within the lung from approximately 35 days post infection*. Note that while low numbers of eosinophils are observed, the inflammation is largely granulomatous and neutrophilic. The pulmonary stages of Aelurostrongylus are readily visible histopathologically, but can also be retrieved in BAL/TTW samples.

Infection of the cat requires ingestion of intermediate hosts (many molluscs) containing L3 larvae. Given the suppurative bronchopneumonia present in these samples, I would not exclude secondary bacterial component, however, early lesions of verminous pneumonia may also be associated by large numbers of bronchiolar neutrophils.

*P.H.G. Stockdale, Pathol Vet 7: 102, 1970.