Felis ISSN 2398-2950

Lungworm disease

Synonym(s): Aelurostrongylus disease, aelurostrongylosis, troglostrongylus, capillaria

Contributor(s): Stephen Barr, Prof Richard Malik, Grace Mulcahy, Severine Tasker


  • CauseAelurostrongylus abstrusus infection is relatively common in domestic cats and is the most important lungworm in cats but other lungworms are now being reported in cats, eg Troglostrongylus brevior, Capillaria aerophila.
  • Signs: many cases are not clinically important.
  • The parasites live in the terminal bronchioles and alveolar ducts (Aelurostrongylus), bronchi and bronchioles (Troglostrongylus) or under the tracheal and bronchial epithelium (Capillaria).
  • Heavy infections can cause dyspnea/hyperpnea and coughing.
  • Diagnosis: detection of larvae of Aelurostrongylus or Troglostrongylus in feces following Baermann examination; they can also be seen in routine fecal flotation and may be seen in bronchial washings or BAL fluid. Similar samples may reveal Capillaria eggs.
  • Treatment: fenbendazole, moxidectin, emodepside, selamectin, eprinomectin and milbemycin appear to be effective in eliminating infections. Routine treatment using these products may be useful to prevent symptomatic infections developing.
Print off the owner factsheet Lungworms in cats Lungworms in cats to give to your client.



  • Most cases are due to Aelurostrongylus abstrusus Aelurostrongylus abstrusus.
  • Most cats tolerate light infection with no clinical signs.
  • Occasionally severe clinical signs occur.
  • Less commonly reported, cases are due to Troglostrongylus brevior or Capillaria aerophila Capillaria aerophila.
  • Troglostrongylus has historically been regarded as a wild cat parasite but it is being increasingly reported in young cats, especially those with possible access to wild cats.
  • Capillaria has also been regarded as a wild cat parasite but more recently reports have occurred in domestic cats. Capillaria can infect other carnivores as well as humans.

Predisposing factors


  • Immunosuppressive factors.
  • General debility.
  • More common in cats with access to outdoors.


A. abstrusus

  • Infected cats may develop bronchial hyperplasia, focal alveolar lung disease and hypertrophy of pulmonary arterioles; a granulomatous or mixed inflammatory response occurs in affected tissues.
  • Secondarily, there is increased mucus in the airways and signs that are indistinguishable from feline asthma Allergic bronchitis.
  • Most natural infections, however, are subclinical.
  • Cats become infected by ingesting L3 in tissues of intermediate (eg slugs and snails, in which the larvae L1 develop to L3) or paratenic (eg rodents, frogs, lizards, snakes, birds, containing L3) hosts.
  • L3 released from tissues of prey penetrate gut wall and migrate to lung via peritoneal and thoracic cavities via hemolymphatic system.
  • After a pre-patent period of 5-6 weeks adult females in the bronchioles, alveolar ducts and alveoli begin laying eggs.
  • Eggs hatch and L1 migrate up trachea, are coughed up and swallowed.
  • L1 are excreted in the feces ready to be taken up by an intermediate host.
  • Effects attributable to host's immune response.
  • In most cases this is not intense.
  • Balanced host-parasite relationship.
  • Occasional clinical cases due to disturbance of this balance.
  • Migration of eosinophils and mast cells into respiratory tract.
  • Hypertrophy and disturbed architecture of pulmonary arterioles most consistent change.

T. brevoir

  • Life cycle of T. brevior very similiar to A. abstrusus with involvement of intermediate and paratenic hosts and L1 excretion in the feces.
  • Some evidence that T. brevior  may be directly transmitted from an infected queen to her kittens.
  • Adults live in the bronchi and bronchioles, causing more severe signs in younger cats with pulmonary edema, congestion, hemorrhage, etc.
  • Pulmonary hypertension Pulmonary arterial hypertension has been reported in a case of T. brevoir infection.

C. aerophila

  • Life cycle of C. aerophila is not thought to involve an intermediate host; earthworms may act as a facultative intermediate or paratenic host but this has not been confirmed.
  • Eggs are excreted in the feces and they become infective in the evironment over 1-2 months, most likely, and are then ingested by a cat.
  • Adults live under the epithelium of the bronchi and trachea.
  • Mostly subclinical infections but pathology includes lesions in the trachea and lung parenchyma.


  • Pre-patent period is 5-6 weeks.
  • Lifespan of adult worms is at least 1 year.


A. abstrusus and T. brevior

  • Transmission depends on cats ingesting intermediate or paratenic hosts.
  • These hosts are ubiquitous.
  • L3 remain viable for long periods in these hosts.
  • Cats are very likely to engage in hunting.
  • A. abstrusus is a common infection in domestic as well as wild cats whereas T. brevoir is particularly common in wild cats.

C. aerophila

  • Transmission by ingestion of eggs from environment but earthworms may act as a facultative intermediate or paratenic host but this has not been confirmed.
  • Particularly common in wild cats.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Lacava G, Zini E, Marchesotti F et al (2016) Computed tomography, radiology and echocardiography in cats naturally infected with Aelurostrongylus abstrusus. J Feline Med Surg 19 (4), 446-53 PubMed.
  • Traversa D & Di Cesare A (2016) Diagnosis and management of lungworm infections in cats. Cornerstones, dilemas and new avenues. J Feline Med Surg 18 (1), 7-20 PubMed.
  • Di Cesare A, Veronesi F, Frangipane di Regalbono A et al (2015) Novel molecular assay for the simultaneous identification of neglected lungworms and heartworms affecting cats. J Clin Microbiol 53 (9), 3009-3013 PubMed.
  • Pennisi M G, Hartmann K, Addie D D et al (2015) Lungworm disease in cats: ABCD guidelines on prevention and management. J Feline Med Surg 17 (7), 626-636 PubMed.
  • Varcasia A, Brianti E, Tamponi C et al (2015) Simultaneous infection by four feline lungworm species and implications for the diagnosis. Parasitol Res 114 (1), 317-321 PubMed.
  • Brianti E, Giannetto S, Dantas-Torres F et al (2014) Lungworms of the genus Troglostrongylus (Strongylida: Crenosomatidae): neglected parasites for domestic cats. Vet Parasitol 202 (3-4), 104-112 PubMed.
  • Di Cesare A, Castagna G, Otranto D et al (2012) Molecular detection of Capillaria aerophila, an agent of canine and feline pulmonary capillariosis. J Clin Microbiol 50 (6), 1958-1963 PubMed.
  • Foster S F, Martin P, Allan G S et al (2004) Lower respiratory tract infections: 21 cases (1995-2000). J Feline Med Surg (3), 167-180 PubMed.
  • Naylor J R, Hamilton, J M & Weatherley A J (1984) Changes in the ultrastructure of feline pulmonary arteries following infection with the lungworm Aelurostrongylus abstrusus. Br Vet J 140 (2), 181-190 PubMed.
  • Losonsky J M, Thrall D & Prestwood A K (1982) Radiographic evaluation of pulmonary abnormalities after Aelurostrongylus abstrusus inoculation in cats. Am J Vet Res 44 (3), 478-482 PubMed.

Treatment studies include the following:

  • Böhm C, Wolken S, Schnyder M et al (2015) Efficacy of emodepside/praziquantel spot-on (Profender®) against adult Aelurostrongylus abstrusus nematodes in experimentally infected cats. Parasitol Res 114 (Suppl 1), S155-164 PubMed.
  • Giannelli A, Brianti E, Varcasia A et al (2015) Efficacy of Broadline® spot-on against Aelurostrongylus abstrusus and Troglostrongylus brevior lungworms in naturally infected cats from Italy. Vet Parasitol 209 (3-4), 273-277 PubMed.
  • Knaus M, Shukullari E, Rapti D et al (2015) Efficacy of Broadline against Capillaria aerophila lungworm infection in cats. Parasitol Res 114 (5), 1971-1975 PubMed.
  • Knaus M, Chester S T, Rosentel J et al (2014) Efficacy of a novel topical combination of fipronil, (S)-methoprene, eprinomectin and praziquantel against larval and adult stages of the cat lungworm, Aelurostrongylus abstrusus. Vet Parasitol 202 (1-2), 64-68 PubMed.
  • Rehbein S, Capári B, Duscher G et al (2014) Efficacy against nematode and cestode infections and safety of a novel topical fipronil, (S)-methoprene, eprinomectin and praziquantel combination product in domestic cats under field conditions in Europe. Vet Parasitol 202 (1-2), 10-17 PubMed.
  • Iiannino F, Iannetti L, Paganico D et al (2013) Evaluation of the efficacy of selamectin spot-on in cats infested with Aelurostrongylus abstrusus (Strongylida, Filariodidae) in a Central Italy cat shelter. Vet Parasitol 197 (1-2), 258-262 PubMed.
  • Traversa D, Di Cesare A, Di Giulio E et al (2012) Efficacy and safety of imidacloprid 10%/moxidectin 1% spot-on formulation in the treatment of feline infection by Capillaria aerophila. Parasitol Res 111 (4), 1793-1798 PubMed.
  • Traversa D, Milillo P, Di Cesare A et al (2009) Efficacy and safety of emodepside 2.1%/praziquantel 8.6% spot-on formulation in the treatment of feline aelurostrongylosis. Parasitol Res 105 (Suppl 1), S83-9 PubMed.
  • Traversa D, Di Cesare A, Milillo P et al (2009) Efficacy and safety of imidacloprid 10%/moxidectin 1% spot-on formulation in the treatment of feline aelurostrongylosis. Parasitol Res 105 (Suppl 1), S55–62 PubMed.