French Heartworm

(Angiostrongylus vasorum)

Angiostrongylus vasorum is a strongylid nematode parasitizing the pulmonary arteries (Fig 1) of dogs and wild canids, responsible for often severe respiratory disorders but also other associated clinical signs. Infection of dogs is via ingestion of intermediate (gastropods) or paratenic (microvertebrates) hosts.

Parasite: Angiostrongylus vasorum
Common name: French heartworm
Host: Canids, rarely other carnivores
Pre-patent period: 6-8 weeks
Location of adults: Pulmonary arteries
Distribution: Europe, North America, South America
Transmission route: Oral [ingestion of intermediate (slugs, snails) or paratenic hosts (frogs, chicken)]
Zoonotic: No


Angiostrongylus vasorum is distributed in Europe, North America and South America (Brazil, Argentina, Bolivia, and Colombia).

Clinical signs

Some cases are asymptomatic, some are symptomatic. Common clinical signs include respiratory disorders (cough, dyspnoea), lethargy, coagulopathy, neurological signs. Chronic cases present also anaemia, weight loss, fever, and weakening.

Figure 1 Angiostrongylus vasorum in the pulmonary arteries of a red fox. (Image credit: Dr. A. D. Mihalca)
Figure 2 First-stage larva of a canine lungworm containing a ‘kink’ in the tail. (Image credit: Dr. R. Traub)


Various approaches are available for diagnosis. Detection of L1 in faeces (Baermann method) is possible during the patent phase of the infection (Fig 2). Differential diagnosis with other larval stages (i.e., Crenosoma, Filaroides) should be made. Various serologic methods are also available, including a rapid in-clinic test for the detection of circulating antigens.


Macrocyclic lactones are effectively used for the treatment of canine angiostrongylosis. Moxidectin (2.5 mg/kg, spot on), repeated after 4 weeks or milbemycin oxime (0.5 mg/kg PO), weekly for 4 weeks. Another option is fenbendazole (25-50 mg/kg PO), daily for 3 weeks. To avoid thrombotic complications, supportive therapy is needed.


Monthly chemoprophylaxis with or milbemycin oxime or moxidectin are recommended in endemic areas. If possible, access of dogs to gastropods or paratenic hosts should be prevented.

Public health considerations