Description
In dogs, Angiostrongylus vasorum (French heartworm) causes canine angiostrongylosis, a potentially life-threatening metastrongyle infection acquired via ingestion of infected slugs, snails, or frogs, leading to adult nematodes in the pulmonary arteries and right ventricle. Clinical signs are highly variable and often respiratory (coughing, dyspnoea, exercise intolerance), progressing to right-sided heart failure (ascites, syncope) in severe cases; coagulopathies manifest as spontaneous bleeding (epistaxis, haemoptysis, gingival haemorrhage), petechiae, or intracranial haemorrhage causing neurologic signs (seizures, paresis, ataxia), while other presentations include abdominal pain, vomiting, lameness, or weight loss.
Diagnosis relies on faecal examination using the Baermann technique to detect L1 larvae (often requiring multiple samples due to intermittent shedding), alongside serum antigen ELISA for circulating adult antigens (highly sensitive in patent infections). Blood (EDTA) is submitted for PCR to detect larval DNA, especially when larvae are absent in faeces, and imaging (echocardiography, thoracic radiographs) supports cardiopulmonary involvement.
Quantitative PCR (qPCR) on blood or bronchoalveolar lavage fluid excels by detecting and quantifying A. vasorum DNA with high sensitivity, confirming active infection, differentiating from other lungworms, and monitoring treatment efficacy.
Crenosoma vulpis (fox lungworm) in dogs causes a milder bronchial infection from ingestion of infected snails or paratenic hosts like frogs, with adult worms in the bronchi and bronchioles. Signs are primarily chronic cough (often productive, “frog-like”), tracheobronchitis, gagging, nasal discharge, and mild exercise intolerance, rarely progressing to pneumonia or severe disease. Cats can be infected but clinical disease is uncommon and poorly documented.
Faecal Baermann examination is the gold standard to identify characteristic L1 larvae, while serology or PCR on blood or respiratory samples provides supportive confirmation. Quantitative PCR (qPCR) on faeces or blood offers sensitive detection and speciation of C. vulpis DNA, distinguishing it from A. vasorum or Oslerus osleri, and is useful for low-burden infections where Baermann may miss larvae.
