Eucoleus aerophilus (Capillaria) in the coughing cat
3-year-old cat that goes into the garden and hunts, with chronic cough and sneezing. Thoracic radiographs show a bronchial pattern. Faecal flotation shows barrel-shaped eggs with plugs at both poles and a reticulated surface; Baermann is negative.
What is the most appropriate interpretation and management?
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A. Eucoleus aerophilus in the trachea and bronchi; treat with an effective antiparasitic (fenbendazole, emodepside or moxidectin spot-on) and repeat faecal testing
Correct. The bipolar-plugged eggs from the airways are swallowed and passed in faeces. Cats become infected by ingesting larvated eggs from the environment or earthworms. It responds to fenbendazole and to macrocyclic lactones or emodepside.
B. Trichuris vulpis; treat as trichuriasis and monitor for colitis
Trichuris vulpis is a dog parasite and whipworms are exceptional in cats. In a coughing cat, bipolar eggs point to Eucoleus.
C. Aelurostrongylus abstrusus, which always sheds eggs in faeces
Aelurostrongylus is detected by L1 larvae on Baermann, not by eggs on flotation. Here the Baermann is negative.
D. An incidental finding (pseudoparasitism from eating prey); treat only the cough with corticosteroids
The combination of cough, bronchial pattern and bipolar-plugged eggs suggests genuine infection. Using corticosteroids alone leaves the parasite untreated.
lightbulb Key takeaway
In dogs, Eucoleus aerophilus eggs can be confused with those of Trichuris vulpis and E. boehmi: look at size, plug symmetry and surface. Eucoleus aerophilus is only exceptionally zoonotic; Pearsonema produces similar eggs in urine.
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Updated: October 31, 2026 · Educational content for veterinary professionals. It does not replace current clinical guidelines or the judgement of the attending veterinarian.