Lung Worm
Lungworm, or Angiostrongylus vasorum to give it its proper name, has been diagnosed with increasing frequency over the last fifteen to twenty years in the UK. Whilst initially cases were very much centred around the south-east of England, they have now been reported all over the UK. A. Vasorum was first reported in France in the nineteenth century and because of this, it is at times referred to as French heartworm (the adult lungworms live in the right side of the heart and its vessels). However, this can become confusing as heartworm in dogs traditionally refers to Dirofliaria immitus which is an entirely separate parasite and as it is not present in the UK, is only of concern in dogs that have travelled abroad.
Lungworm larvae are found in hosts such as slugs and snails (as well as, more rarely, frogs) and dogs become infected by ingesting those hosts. There is some thought that the larvae may be found in the environment as well (e.g. in a snail trail). Once ingested the larvae travel around the body and undergo further life stage changes. Dogs can excrete larva in their faeces without becoming symptomatic for up to two years if left untreated.
What to look for
The clinical signs seen with lungworm are broadly split into two categories – those affecting the cardio- respiratory system (the heart and lungs) – which is most common – and those causing a clotting problem (meaning that affected patients are prone to bleeding). Dogs with cardio-respiratory signs tend to show coughing due to the physical presence of the larva in the lungs as well as an associated pneumonia (inflammation) of the lungs themselves. They can also show hypertension (high blood pressure), bleeding and neurological signs. Less commonly clotting problems are seen. The reason for this is multifactorial and not well understood but the signs normally seen include bruising on the skin and bleeding in the sclera (or ‘whites’) of the eyes.
Lungworm infection can be diagnosed by looking for the parasite in faecal samples or respiratory secretions as well as via a blood test and those results should be considered in conjunction with supportive clinical signs and x-ray changes of the lungs.
Treatments
There are licensed treatments available in the UK to treat lungworm (in both topical spot-on and tablet form). Other supportive therapies can be required such as antibiotics for secondary infections and blood transfusions for severe bleeding.
In areas deemed high risk, preventative tablet medication can be used alongside other measures such as restricting access to areas where slugs and snails are found, removing faecal matter regularly (as the parasite can be shed in faeces) and keeping toys inside overnight to avoid them becoming covered with snail/slug trails.
Thankfully lungworm remains a relatively uncommon disease, especially in the North West, but it is important to be aware of as prompt diagnosis and management can make a big difference to recovery.
Helen Hewitt (Veterinarian)
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