Lungworm - Is your dog at risk?
In recent years a new parasite has become more prevalent in the local area. Angiostrongylus vasorum, or lungworm used to be considered a problem confined to the South West and Wales but it has been increasingly diagnosed in dogs in our area.
How are dogs infected?
This nasty parasite infects dogs when they eat infected slugs, snails or frogs. Some dogs will eat these slimy creatures on purpose (presumably they like the texture!) but most are incidentally infected while eating grass or chewing on toys under which a slug or snail is sheltering in the garden. Most, but by no means all of the dogs seen with this condition are young – it is believed this is due to their inquisitive nature.
When a dog is infected the adult worms live and reproduce in the heart and blood vessels of the lung. They lay eggs which hatch to larvae, which are then coughed up and swallowed. They pass through the dog’s digestive tract and out in its faeces. Slugs and snails are infected by ingesting (eating) the larvae which have contaminated the environment. These creatures are then consumed by a dog (or fox, which can act as a reservoir for the parasite) and the cycle begins again.
What are the clinical signs of lungworm?
Some dogs develop signs of coughing, reduced exercise tolerance or breathlessness. These signs are associated with the presence of the worms in the heart and large blood vessels and the damage done to the lungs as the larvae work their way out. Some dogs, however, do not show these signs but develop even more worrying problems. The presence of lungworm can lead to poor blood clotting, which means that these unfortunate dogs sometimes present with bleeding problems. Neurological (nervous) signs such as seizures (fits) and back pain can also be seen. If left untreated these problems can be life threatening.
How is lungworm diagnosed?
Definitive diagnosis is made by identification of the larvae which are immature worms (figures 1a
and 1b), usually by looking at a sample of faeces from the affected dog but also sometimes by looking at washes taken from the lungs by the vet (a technique known as broncho-alveolar lavage). X-rays (figures 2a and 2b), endoscopy where a camera is put down into the airways (figure 3) and other blood tests may also be required in investigation of this condition. Occasionally we may ‘test treat’ for lungworm when we suspect it could be causing a problem but we are unable to identify the larvae.
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Figure 1a (X100; Gram stain) Figure 1b (X40; Wrights stain) |
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Figure 2a |
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Figure 2b After treatment |
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Figure 3 |
Treatment
Although treatments are now available, unfortunately some dogs may still die despite diagnosis and appropriate therapy.
Prevention
With such worrying clinical signs associated with lungworm, prevention is obviously better than cure. There is now a spot-on product called Advocate which, when used monthly, prevents lungworm in dogs. This product also treats fleas and round worms, so it could be used as a routine wormer/flea prevention in dogs that are considered at risk from getting lungworm. (Please note this product does not kill tapeworms and so additional tapeworm treatment may be required). If you think your dog may be at risk of lungworm please discuss this with the vet.
Apart from regular medication, other tips for reducing risk of your dog becoming infected include cleaning toys which have been left out and keeping them inside; not leaving food or water bowls outside, or if this is necessary then cleaning them daily. Please note that you are unlikely to significantly reduce the slug and snail population in your garden by using excessive quantities of slug bait. Slug pellets, which contain metaldehyde, are extremely toxic to dogs and should be used with extreme care – if at all – when pets or children are around (see our Poisons and household dangers information sheet)
If you are concerned about lungworm in your dog then please do not hesitate to contact us.
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