Case summary A 9-year-old, male neutered, indoor–outdoor domestic shorthair cat from the northern Alabama countryside presented for a 3 week history of coughing, lethargy and an episode of self-resolving dyspnea that occurred 1 week prior to presentation. Three-view thoracic radiographs revealed a moderate-to-severe, diffuse, mixed bronchial to structured interstitial (miliary-to-nodular) pulmonary pattern in all lung lobes with peribronchial cuffing and multifocal areas of mild patchy alveolar opacity. Ultrasound-guided evaluation and fine-needle aspiration of the caudodorsal lung parenchyma was performed with sedation. Cytology revealed many widely scattered Aelurostrongylus abstrusus larvae and ova. Upon the confirmed diagnosis of A abstrusus verminous pneumonia, treatment with fenbendazole and selamectin resulted in complete resolution of clinical signs within 6 weeks of the initial diagnosis.

Relevance and novel information We report herein the first documented case in the Americas of A abstrusus verminous pneumonia diagnosed via cytologic evaluation of an in vivo, percutaneous ultrasound-guided fine-needle aspirate of affected lung. Additionally, to our knowledge, we offer the first account of the sonographic (pulmonary) features of the disease.