Lungworms are a group of parasites that can affect both dogs and cats. Lungworms are much less common than parasites such as fleas, ticks and tapeworms, but the associated problems with a Lungworm infection can be far more severe than with other more common parasites. Canine and Feline Lungworms cannot be transmitted to people.
In the past, Lungworms were only found in a few places in the UK, but over the last few years they have become much more widespread across the whole of Britain including the Thames Valley region. It is unclear exactly what has caused the spread of Lungworms (and other parasites) but increased movement of pets around the country, as well as an increase in wildlife in urban environments is thought to play a big part; it is also thought that the recent mild temperatures and rainy weather has helped the spread.
Lungworms infect dogs when they ingest the intermediate host which is a slug, snail, frog or other mollusc and infect cats when they ingest a rodent or bird that has previously ingested a slug, snail, frog or other mollusc carrying the Lungworm larvae.
Fortunately there are treatments available from your veterinary practice that are easily applied and will prevent this parasite from becoming a hazard to your pet.
There are two types of Lungworm that commonly affect dogs in the UK, Angiostrongylus vasorum and Crenosoma vulpis.
Canine Lungworm Life Cycle
- Slugs and snails eat the immature Lungworm larvae while feeding on the faeces of infected dogs or foxes.
- The dog ingests the slugs, snails or other molluscs that may be harbouring the larvae .
- Once inside the dog, the larvae penetrate the dog’s intestinal wall and start to develop in the abdominal lymph nodes.
- The larvae then migrate through the body; the Angiostrongylus vasorum Lungworms enter the dog’s circulatory system and travel to the right ventricle of the heart and the pulmonary arteries of the lungs. The Crenosoma vulpis Lungworms travel directly to the dog’s lungs.
- Once they are in place the Lungworms start to mature; growing up to 2.5cm long.
- The female Lungworms produce eggs that lodge in and develop in the capillaries of the lungs.
- Larvae hatch from these eggs and move into the lung airspace. It is at this stage when the larvae can produce clinical signs such as coughing and breathing difficulties
- They are then coughed up and swallowed to be passed out in the dog’s faeces, allowing the cycle to begin again.
Canine Lungworm Clinical Signs
The main difficulty with the diagnosis of Lungworm is that some dogs may not show any clinical signs at all. In the majority of healthy dogs that become infected the parasite runs through it’s life cycle, with the dog showing intermittent and non-specific signs such as lethargy, inappetence, weight loss, nasal discharge and occasional vomiting. These signs sometimes progress to coughing, difficulty breathing and reduced exercise tolerance.
In the worst cases the parasite can prevent blood from clotting properly so that a dog may cough up blood, have nose bleeds or any wounds it has may not stop bleeding. Lungworm can also affect the dog’s nervous system and cause lethargy, spinal pain, paralysis, fitting and can be fatal.
Is Your Dog At Risk?
All dogs are at risk of a Lungworm infection, but those most susceptible will be
- Those who are known to eat slugs, snails, frogs etc (usually young, inquisitive dogs)
- Dogs that eat grass; these dogs can accidentally ingest small slugs or snails
- Dogs whose toys and bowls are left out in the garden. Some slugs and snails are so small they are often unknowingly consumed.
The lungworm that commonly infects cats in the UK is called Aelurostrongylus abstrusus, it is rare in the UK but more cases are confirmed every year.
Feline Lungworm Life cycle
- Adult feline lungworms, Aelurostrongylus abstrusus, measure up to 1cm in length and lay their eggs in the lung tissue or the walls of the blood vessels around the lungs.
- The larvae released from the eggs then migrate up the trachea (air passage) and eventually reach the pharynx where they either swallowed into the digestive tract or coughed up onto the ground.
- The larvae that were coughed out or are expelled in the cat’s faeces are eaten by slugs or snails in which they develop.
- The slugs and snails may then be eaten by birds or rodents, which are in turn eaten by the cat and pass the parasite on so it can start its lifecycle again.
Feline Lungworm Clinical Signs
Many cats never show signs of the infestation and some cats can develop a natural immunity to the Lungworm. After three or four months the lungworms are expelled from the cat’s body leaving the cat resistant to further infection, although whilst this immunity is developing the lungs of an affected cat can be literally riddled with worms, larvae and eggs which can have quite an impact on the cat’s health.
When symptoms do occur, they can come on quite quickly and severely and the cat may be coughing, have difficulty breathing and be in poor general condition (similar to cat flu symptoms).
Is Your Cat at risk?
Feline Lungworm is mainly seen in cats who hunt birds and rodents.
Diagnosing A Lungworm Infestation
- Symptoms – the vet may make a suspected diagnosis based on the symptoms of the dog or cat.
- Blood Test – there is a blood test available for dogs that can tell us if the Angiostrongylus vasosum lungworm is present. Unfortunately blood tests have not been developed for the other lungworms yet.
- Faecal test – the vet may request faecal samples from your pet to look for Lungworm larvae. However, because of the life cycle of the lungworm the larvae will not always be present in the animal’s faeces, even if the animal is infected.
- X-ray – the vet may X-ray your pet’s chest to look for signs of Lungworm.
- Bronchoscopy – A small camera can be passed down the throat to view the lungs and look for the presence of lungworm.
Treatment For Pets With Lungworm
Treatment is available for Lungworm once it has been diagnosed but sadly, in rare cases of heavy infestation or associated complications, the cat or dog still may die from this parasitic infection. Prevention is the key here and it is easy to achieve with a monthly spot on treatment available on prescription.
Fortunately Lungworm is preventable by the use of a prescription spot-on treatment that is applied monthly and is available at your veterinary surgery; Castle Vets offers this treatment routinely as part of our Pet Health Club membership. The spot on treatment also kills fleas and some other intestinal worms, so it can replace your usual product if your pet is at risk. If you think that your dog or cat is at risk please speak to your veterinary nurse who can advise you on preventative treatment
Doing the following will also help reduce the risk of lungworm
- Scoop the poop. Lungworm larvae are passed out in dog faeces, so if we pick up after our pets we can help prevent the spread of these parasites.
- Pick up toys. Toy’s left outside overnight are exposed to slugs and snails. Pick up your dog’s toys at the end of each day and store them in a container or bring them inside.
- Don’t leave food and water bowls outside. Bowls left outside will be exposed to slugs and snails so it is a good idea to clean them and bring them inside.
Lungworm.co.uk for news and information about Lungworm.
It’s A Jungle Out There for news about all kinds of pet parasites.