Is Feline Lungworm on Your Veterinary Radar?

If feline lungworm isn’t already on your radar it should be! Bayer recently presented the latest research and expert opinions on feline lungworm at the ISFM Congress 2019, providing insights into the diagnosis of Aelurostrongylus abstrusus and the treatment and control of the different lungworm species – which are all of growing concern in feline medicine.

Three main parasites can infect the feline respiratory system; Aelurostrongylus abstrusus, Troglostrongylus brevior and Capillaria aerophila. A recent study has shown the combined prevalence of the feline lungworm parasites to be 10.6% in European domestic cats.1 Which means there is a call for veterinarians to be on the lookout for these parasites as a cause of respiratory disease in cats.

Practitioners should be aware of the importance of lungworms. Current knowledge demonstrates that all cats with respiratory signs must be examined for more than one lungworm.


Feline lungworms are often underdiagnosed
Feline lungworms are often underdiagnosed but potentially fatal parasites.


Professor Manuela Schnyder, University of Zurich, Switzerland, a parasitologist and speaker at the Bayer symposium highlighted this with A. Abstrusus specifically: ‘’The prevalence of lungworm infections in cats caused by the parasite Aelurostrongylus abstrusus is generally underestimated. It should always be considered, especially in cats showing respiratory signs, however, pathological changes may also occur when no clinical signs are apparent.’’

Professor Schnyder then went onto explain the significance of this to veterinarians in practice, as there are reports of cases that have only become apparent when issues are encountered during anaesthesia for routine surgeries.

However, diagnosis of feline lungworm isn’t always straightforward, the clinical signs and thoracic radiography changes can be non-specific, sometimes leading to a misdiagnosis of feline asthma or chronic bronchial disease. Relying on the detection of L1 in faeces may result in false negatives as shedding can be absent or intermittent, even when clinical signs are evident. There can also be difficulties in obtaining fresh faecal samples from outdoor cats and it has been found that samples from litter trays may compromise results.2,3 Serology can be useful in these cases.


cat outside
Healthy cats exposed to risk factors should be screened regularly for lungworms.


Identification of the causative agent is necessary for the management of diseased cats.

Professor Donato Traversa, EBVS® European Veterinary Specialist in Parasitology, University of Teramo, Italy explained during the symposium: “While Aelurostrongylus abstrusus remains the most important nematode affecting the cardio-respiratory system of cats worldwide, with a prevalence of 8.2% within Europe; Troglostrongylus brevior and Capillaria aerophila should not be forgotten, and diagnosis to species level is advised to enable the appropriate treatment to be selected.”  

Regardless of the presence and severity of clinical signs, the administration of an efficacious parasiticide is required in all cases when a respiratory parasitosis is diagnosed.

There is also a recommendation from experts that prevention would be best practice in endemic areas, although currently there is no licensed product available for this. It is also important for veterinarians to remember that recent and repeated anthelmintic treatment does not exclude lungworm infection, a product is required which has persistent efficacy.


Veterinarians are able to treat Aelurostrongylus abstrusus and Capillaria aerophila in Europe with widely available licensed anti parasitic treatments. Bayer is proud to hold five IFSM easy-to-give awards with our range of parasiticides, including most recently Seresto® – marking Bayer’s commitment to providing effective parasite treatment and prevention solutions for cats.

Guidance for veterinarians managing Feline Lungworm in practice

  1. Consider feline lungworm as a cause of respiratory disease in cats, especially those with outdoor access. While the clinical signs can be non-specific, ranging from asymptomatic to severe respiratory distress, the most common clinical sings are a chronic cough, sneezing, nasal discharge and dyspnoea.
  2. Be aware that cats with asymptomatic infections can be at risk of severe acute respiratory distress in the peri-operative period - recent and repeated anthelmintic treatment does not exclude lungworm infection.
  3. Remember false negative results are possible with faecal screening, consider serology in these cases.
  4. Appropriate parasiticides and protocols should be selected on a case-by-case basis because some of the available products have different efficacies against the different lungworms.




1.    Giannelli A, Capelli G, Joachim A, et al. Lungworms and gastrointestinal parasites of domestic cats: a European perspective. International Journal for Parasitology. 2017;47(9):517-528. doi:10.1016/j.ijpara.2017.02.003.
2.    Gueldner E, Gilli U, et al. Seroprevalence, biogeographic distribution and risk factors for Aelurostrongylus abstrusus infections in Swiss cats. Veterinary Parasitology. 2019;266:27-33
3.    Abbate J, Afruso F, et al. Larval survival of Aelurostrongylus abstrusus lungworm in cat litters. Journal of Feline Meicine and Surgery. 2018