Lungworm in dogs – an increasing threat

By Fintan Browne, veterinary surgeon in Blanchardstown Veterinary Hospital

It appears that lungworm infections are on the rise. In the past number of weeks I have had 3 lab-confirmed cases of Angiostrongylus vasorum – or “lungworm” as it is more commonly known – in dogs visiting our Anicare hospitals (2 in Blanchardstown and one in our Glasnevin branch). Dogs are typically infected by eating small slugs and snails (or less commonly frogs) and it is something that suburban pets can easy pick up in their own back gardens. When a dog eats the infected intermediate hosts the parasite continues its complex lifecycle and the worms mature and live in the blood vessels close to the lungs and the heart. From here they lay eggs which develop into larvae that penetrate into the small airways of the lungs from where they are coughed up and swallowed. Finally these larvae are passed in the dogs faeces, and then can re-infect slugs, snails and frogs in the environment.

Diagram of Angiostrongylus vasorum life cycleDiagram of Angiostrongylus vasorum life cycle

Angiostrongylus infections can cause a myriad of different clinical signs in an infected dog. It is one of the few pet parasites we have in Ireland that can frequently have fatal consequences. Because the adult worms live inside blood vessels they affect blood clotting. Many dogs we see with this condition develop bleeding disorders, and this is often the reason they are presented to us in the first place. Other symptoms can include coughing, breathlessness and sometimes neurological problems (if the animal haemorrhages into its brain or spine).

The case I saw this morning was a young dog that had developed a harsh productive cough over the past few days. It had very little contact with other dogs which made typical infectious bronchitis – which is common in dogs – unlikely in this case. The dog kindly provided me with a large phlegm sample (by coughing it up at my feet). I immediately placed a drop of this on a glass slide and examined it under the microscope. Angiostrongylus infections can often be very difficult to diagnose but in this case I was able to identify the microscopic parasite larvae swimming about in the dog’s phlegm! It it always very rewarding to be able to actually see the pathogen responsible for an animal’s illness, which is probably why I am so attached to my old Leitz microscope. Here’s a link to a video of this morning’s star pathogen:

Happily the condition is treatable and this morning’s patient should do very well. However without a quick diagnosis and prompt treatment the dog’s outlook would have been much worse. Some routine parasite treatments can also be used to help protect against lungworm infections in dogs, any of our vets and nurses will be able to advise you on how to best protect your pet.

Fintan Browne

About Fintan Browne

Fintan Browne is a vet in Anicare Veterinary Group in Dublin and is the Chairperson of the Veterinary Ireland Companion Animal Society, the representative group for Ireland's 'Pet Vets'.

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