Lungworm in Dogs: What all Dog Owners Need to Know

Medically Reviewed by Dr Pippa Elliott

Last Updated on

Lungworm in UK dogs

Are you lungworm aware?

Perhaps you’ve heard of lungworm in dogs but feel vaguely confident your dog is protected. Unfortunately, complacency kills and puts your dog at risk because this potentially deadly infection has spread countrywide.

To find out if your dog is at risk, see how many of the following questions you answer “Yes” to:

  • Are there foxes in the area?
  • Is lungworm in your area?
  • Do you live in a lungworm hotspot?
  • Does your dog roll in fox poop?
  • Does your dog have contact with slugs and snails?
  • Do you leave dog toys out in the garden?
  • Does your dog eat grass?
  • Are you behind with regular preventative treatment or worming against lungworm?

If you answered “Yes” to ANY of those questions, then lungworm could pose a danger to your dog. This parasite has a complex lifecycle involving foxes, infected slugs, and snails; any of which are potential sources of infection for dogs. The devastating consequences of which can be haemorrhage and death from blood loss.

Is Lungworm in your area?

Lungworm used to be restricted to certain local areas, but now it is found countrywide, including Scotland and Wales.

uk lungworm map

Click on the map to search

What is Lungworm?

A parasite called Angiostrongylus vasorum is responsible for lungworm infections. (Actually, the common name, lungworm, is misleading because Angiostrongylus isn’t specifically a lung worm but rather a parasite that invades the heart and major blood vessels.) The lungworm parasite is different to heartworm (a condition prevalent in the US), but is equally as serious.

Lungworm used to be a local disease, confined to small areas in the south-west of England. It is largely spread by foxes, and the unchecked rise in the urban fox population means this once rare condition is now common. Indeed, experts now warn that the spread of the parasite is such that any dog in the UK should be considered at risk.

“The prevalence of lungworm in dogs is increasingly common.”

Ruth Willis: MRCVS, Cardiac specialist.

Imagine a Disease Designed to Kill Dogs

Imagine you are tasked with designing a killer disease to infect a large numbers of dogs. What factors would you consider helpful? Here are a few suggestions:

  • Easy for dogs to catch
  • Can be spread locally by common garden arthropods (slugs and snails)
  • Carried over large areas by wild animals (foxes)
  • Minor symptoms until dangerous numbers are reached in each dog
  • Sudden and catastrophic bleeding leading to death

Yep, that pretty much sums up lungworm and how infectious it can be.

How do Dogs get Lungworm?

Knowledge is power when it comes to minimising risk, so let’s take a quick look at the lungworm life cycle.

The dog picks up infection by eating larvae in infected slugs, snails, or snail-slime. The larvae migrate through the gut wall via the liver into the main vein entering the heart to reach its preferred location, the right ventricle.

The adult worms produce more eggs, which hatch and migrate through the lungs, where they are coughed up, swallowed, and pass out in the dog’s poop. More slugs and snails can become infected by contact with those infected faeces or infected fox poop.

Thus dogs eating slugs are at risk, as are those that eat grass or play with toys over which a snail-trail has been left. This is because under certain weather conditions, lungworm larvae can survive in the slime.

“If untreated this [lungworm] can be fatal to dogs, usually due to uncontrolled bleeding.”

Ruth Willis: MRCVS, Cardiac specialist

Lungworm Symptoms

In the early stages of lungworm infection the dog may show no clinical signs or display only vague, non-specific symptoms such as:

  • Lack of energy
  • Poor appetite
  • A cough
  • Diarrhoea
  • General sickness

As the number of worms multiply inside the blood vessels and heart, and then start to migrate, the cough may worsen and the dog’s breathing become rapid and heavy.

More advanced symptoms of lungworm include:

  • A swollen belly
  • Distressed breathing and breathing problems
  • A profound lack of energy
  • Weight loss
  • A severe cough
  • Seizures
  • Anaemia (a condition in which there is a deficiency of red cells or of haemoglobin in the blood)
  • Poor blood clotting and haemorrhage

Unfortunately, the worms are well adapted to life in blood vessels and protect themselves by producing a factor which interferes with blood clotting. Once enough of this anticoagulant has built up in the blood stream, the dog may bleed heavily from minor scratches or bumps.

Indeed for the dog that starts to cough blood the future is very grim indeed, and some dogs have died from minor injuries such as a broken toe nail that refused to stop bleeding, leading to profound anaemia, and death.

How is Lungworm Diagnosed?

Fortunately, vets now have a simple ‘one spot’ blood test which gives a quick Yes / No answer as to whether a dog has lungworm. This test is used not only in dogs showing signs of lungworm but also in those undergoing routine surgery to screen then prior to a procedure such as neutering where good blood clotting is essential. [2]

When a dog tests positive for this parasitic worm then the vet may suggest chest x-rays to assess lung damage. Also, for dogs that are sick with lungworm, the vet may need to assess the damage already done to blood and the organs.

To this end they may run screening blood tests to check if a blood transfusion is necessary, and an ultrasound scan of the heart to see if permanent damage has occurred.

Lungworm Treatment

In cases of lungworm the treatment is a two-pronged attack aimed at killing the Angiostrongylus whilst dealing with problems such as blood loss or heart failure. As you might suspect, treating lungworm is not without complications, one of which is dead worms in the circulation causing foreign body reactions and pneumonia.

Actual lungworm treatments are the same as the preventatives (see the next section). In addition the dog may need:

  • A blood transfusion to replace lost blood
  • Steroids to prevent the immune system going into overdrive due to the presence of dead worms in the blood stream
  • Antibiotics to treat secondary pneumonia
  • Heart meds such as diuretics to improve how the damaged heart works.
    All in all it’s clear that infection is undesirable and prevention is much the better option.

Lungworm Prevention

Happily prevention is easy for the diligent owner as there are several products known to be effective at killing larvae straight after ingestion.

These include:

Advocate 

Active ingredient: moxidectin and imidacloprid.

This spot-on treatment is licensed for both the treatment and prevention of lungworm. It should be applied once a month, every month.

Milbemax

Active ingredient: milbemycin.

This is a tablet which is licensed for the prevention of lungworm when given once a month, and as a treatment it should be given weekly for four weeks.

Panacur (Fenbendazole)

Active ingredient: anthelmintic, fenbendazole.

In addition, Panacur (Fenbendazole) may be used to treat infection when given daily for 21 days. All of the above are regular worming treatments that are effective not just against adult lungworm but other common parasites such as roundworms.

Note, these are all prescription products and require a prescription from your vet.

Be Lungworm Aware

Reduce the risks of your fur-friend contracting lungworm by taking the following steps:

  • Dog owners should consider de-slugging their garden (Safely of course! Take care with slug pellets)
  • Don’t leave toys or water bowls out for slugs and snails to crawl over
    Stop your dog rolling in fox faeces
  • Use an approved preventative product such as Advocate or Milbemax, once a month, every month.

Is this a problem you were aware of or has your dog had a lungworm scare? Leave a comment and share your experiences with the DDT community.

For more extensive information on lungworm in dogs visit Lungworm.co.uk

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