What is it?
Lungworm is a really nasty parasite, that can prove fatal to infected dogs. It is now being increasingly diagnosed, due to the roll-out of a new blood test for the parasites.
What causes it?
The Dog Lungworm, Angiostrongylus vasorum, is a type of roundworm that (as and adult) lives in the blood vessels around your dog's heart. From here, they lay eggs which travel to the lungs, where they hatch. The baby larvae are then coughed up by the dog, swallowed, and pass out in their faeces. Once out of the dog, they infect passing slugs and snails. These molluscs then spread the infective (L3) larvae in their slime trails wherever they go. When a dog licks a slime trail - or eats a snail or slug - the larvae burrow through their gut wall and travel back to the lungs, ready to start the cycle again.
What dogs are at risk?
Lungworm is present throughout the UK; however, its distribution is quite patchy. Some areas see a lot of cases, while others just a mile or two over may see them only very rarely. However, in principle, any dog, anywhere in the UK who ever has access to the outdoors (and therefore to slugs and snails) is potentially at risk.
What are the symptoms?
The most common early sign is a soft, moist cough (as the dog is coughing up the larvae). However, this may progress to heart failure (pale gums, reduced exercise tolerance, even collapse) as the worms build up in the blood vessels. In addition, more worms means more lung damage, so difficulty breathing may also occur. To be able to live in the bloodstream, the worms produce blood-thinners, so abnormal bleeding may also be seen, typically bruising, a rash (on the skin or gums), or bleeding from nose, mouth or bowels. If this stage is reached, affected dogs will usually die if untreated.
How is it diagnosed?
The "Gold Standard" test has always been considered finding the worm larvae in the dogs faeces; however, there is now a simple blood test that can be carried out in the practice lab to see if a dog is carrying the worms and therefore may need treatment - whether or not they are showing symptoms yet.
How can it be treated or managed?
The worms can easily be killed with certain prescription spot-on medications. If there is a severe infection, it may be necessary to give anti-inflammatory drugs as well, to prevent pneumonia happening as the worms die in the lungs. Dogs with heart failure will usually make a complete, or nearly so, recovery once the worms are dead, although they may require oxygen and supportive care in the meantime. Dogs with clotting disorders may require a blood transfusion as well, to replace the clotting factors and the blood that they are losing.
Can it be prevented?
Yes - regular treatment with an appropriate spot-on or tablet medication will kill the larvae before they are absorbed. In addition, making sure that your dog doesn't play with slugs or snails; or have any toys or bowls that they might crawl over, will minimise the risk.