Troglostrongylus brevior: a severe lungworm in kittens
Litter of 7-week-old kittens born to a queen with outdoor access in Mallorca. Two have cough, nasal discharge and severe dyspnoea; one has died. Faecal Baermann shows metastrongylid L1 larvae.
Which statement about Troglostrongylus brevior is correct?
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A. It lives in the lung parenchyma and causes mild disease in adult cats, like Aelurostrongylus
Troglostrongylus lives in the trachea and bronchi, not the parenchyma, and its hallmark is severity in kittens and young cats.
B. Its L1 are identical to Aelurostrongylus, so there is no point differentiating them
The L1 of the two can be distinguished by tail morphology or PCR, and telling them apart matters for prognosis in kittens and possible vertical transmission.
C. It only responds to fenbendazole for 3 months; macrocyclic lactones are not effective
Good results have been reported with emodepside and moxidectin spot-ons. A treatment this long is not required as the only option.
D. It parasitises the trachea and bronchi, causes severe and even fatal disease in kittens, and vertical transmission from the queen is suspected
Correct. Its larger size and location in the large airways cause severe disease in young cats. Illness in suckling kittens suggests vertical (probably transmammary) transmission. Treat the whole litter and the queen with an effective antiparasitic.
lightbulb Key takeaway
Troglostrongylus brevior comes from the European wildcat and is present across the Mediterranean basin, including Spain. With metastrongylids in very young cats, think of it, treat the litter and the queen, and repeat the Baermann after treatment.
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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.