circle SPONSORED described with bronchial thickening with a multifocal and / or peripheral alveolar pattern. A retrospective study investigating computed tomography findings in naturally infected dogs found that the predominant abnormality was increased lung attenuation due to poorly defined ground-glass opacity or consolidation, with a predominantly peripheral distribution. The study concluded that in cases with a primarily peripheral distribution of pulmonary lesions, A. vasorum infection should be included in the imaging differential diagnosis list [ 10 ]. Of course, all these findings are not pathognomonic and a significant overlap with other pulmonary conditions exists.
Diagnosis method, as larval shedding may be intermittent, and therefore larvae may be missed in a single sample. Please note that in acute infection, dogs may demonstrate clinical signs before L1 larvae are present in the faeces.
• Bronchoscopy and bronchoalveolar lavage( BAL) may be beneficial if the dog is showing cardiorespiratory signs. However, some dogs may be positive on BAL and Baermann negative. BAL requires general anaesthesia and there are some risks associated with the procedure.
• Cerebrospinal fluid( CSF) samples have also demonstrated the presence of larvae.
Making a diagnosis of A. vasorum infection should be based on the presence of a compatible history and clinical signs, along with one or more of the following confirmational tests:
• A bedside Angio Detect test( IDEXX). This test detects circulating adult antigen in blood. It is rapid( results are obtained in less than 15 min) and easy to use. The sensitivity of Angio Detect is relatively high( 85 – 97.1 %) and its specificity is excellent( 98.9 – 100 %) [ 11 ]. Yet, these values were generated in a study where the test was compared to faecal Baermann testing as a gold standard. As such, the test ' s performance may not be quite so high in a clinical setting. In practical terms, a positive result is a very reliable value but a negative result in a case highly suspicious for disease should be followed up with an alternative diagnostic test or retesting a later date, if safe to do so.
• New molecular techniques and antibody-based assays have been described but are not yet widely commercially available.
• A direct microscopic faecal smear examination. This is a quick and easy way to demonstrate L1 larvae but is prone to false-negative results [ 12 ]. To make such a smear, a small quantity of faeces, often obtained via a direct rectal examination, should be placed on a clean microscope slide. Mix this with a few drops of water or 0.9 % NaCl( saline) and place a coverslip over the smear. The faecal material should not be left in a lump in the centre of the coverslip but evenly spread so that the microscope light can shine through. A. vasorum larvae( Figure 3) can be differentiated from other lungworm larvae by morphological characteristics, but stating this differentiation with confidence may require a specialised parasitologist.
• A modified Baermann examination is the preferred method for demonstrating the presence of larvae in faeces. Faeces should be collected in three samples to increase the sensitivity of this
Figure 3. L1 Angiostrongylus vasorum larva in the faeces of an infected Scottish dog.
Predicting perioperative bleeding risk and testing in‘ asymptomatic’ dogs
The potential for bleeding during surgical procedures, including routine operations such as neutering, can be considerable, even in dogs that show no obvious clinical signs of infection. Given the widespread presence of A. vasorum across the UK, this risk should be considered by small animal practices prior to any elective surgery, and the possible implications should be clearly discussed with owners in advance.
One strategy would be to carry out pre-surgery screening of all dogs that do not have a known history of anthelmintic treatment effective for A. vasorum, using an in-clinic diagnostic test such as the Angio Detect test. If a dog tests positive for A. vasorum, surgery should be postponed and appropriate supportive care provided as necessary, alongside treatment with a licensed anthelmintic.
Volume 41( 2) • April 2026
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