As a vet, canine Lungworm (Angiostrongylus vasorum) is a very worrying parasite indeed. Infections seem to be increasing in number, and the fact that the parasite can cause a whole range of symptoms makes it very difficult to diagnose. Although the parasite is very easy to treat and prevent, animals can die as symptoms range from coughing to bleeding disorders and seizures. The parasite is often considered as much more of a life threatening condition than other intestinal parasites, as it’s more likely to cause fatalities.
How do dogs become infected?
Dogs become infected when they eat slugs and snails that carry the lungworm larvae. It’s thought foxes play a part in the parasite’s life cycle. As urban foxes are becoming more and more common, it’s thought that this is why cases of lungworm are on the rise. Although any dog can suffer from lungworm, young dogs seem to be more prone. This is because young dogs are more likely to eat slugs and snails whilst exploring their environment. Some owners are aware that their dogs commonly eat slugs and snails (they just seem to like them!), and so these dogs are also at a high risk!
As you would expect, incidences of lungworm arise more in the wet, damp months when we see a large number of slugs and snails. Worryingly, it’s also thought that dogs may catch lungworm from ingesting the trail from an infected slug. Slugs and snails will often crawl across pet water bowls/ food bowls/ toys that are left outside. We advise that all dogs be preventatively treated, as it’s virtually impossible for owners to take their dogs to slug and snail free areas. Frogs are also involved in the spread of the disease, but we’re unsure how big of a part this plays in the infection of our dogs.
What are the symptoms?
Often, dogs don’t show visible signs of infection until it’s too late, but signs to look out for include:
- Breathing difficulties
- Blood spots appearing on the body or whites of the eye
- Nose bleeds
Diagnosing lungworm can be difficult - your vet will need to look for worm eggs in your dog’s windpipe or in faecal samples. As the worm intermittently sheds eggs, it’s not possible to completely exclude lungworm as a diagnosis if an egg count comes back as negative. Usually, diagnosing the condition is based on the visible signs that your pet will show, and their response to treatment.
How does lungworm work?
The adult worm’s habitat of choice is the blood vessels that supply the heart and lungs of foxes and dogs. This is why the condition causes the range of signs listed above. As well as causing problems by moving through the dog’s blood vessels, adult worms also secrete a substance that stops the blood clotting. The adult worm can even cause pneumonia as it moves through the lung tissue. Its eggs are then laid and coughed up by the dog, swallowed again and then passed into the faeces - ready to infect a slug or snail. The young worms don’t cause problems, and it’s this stage of the worm’s lifecycle that is completed in the slug and snail population. Remember, dogs become infected by eating infected slugs/snails/trails and so the disease isn’t passed from dog to dog. However, if one dog in a house is affected by lungworm, it’s wise to treat any other dogs in the house, as all of the dogs may have been in contact with infected slugs and snails.
Treatment of lungworm involves treatments that kill the parasite itself, along with treatments that help alleviate the signs that your pet may be showing. Most dogs go on to make a full recovery if diagnosed and treated promptly. Again, it can be difficult to treat lungworm due to the wide range of ways it presents itself, and so the disease can prove fatal in some cases.
What about cats?
Owners are often concerned about the risk of lungworm to their cats. Cats do get their own ‘type’ of lungworm. Infections in cats seem to not only be much rarer, but don’t cause the severe signs shown in canine infection. It’s also natural for us to worry about the risk of lungworm spreading to humans. Lungworm doesn’t pose a threat to humans, although other canine worms do cause disease in people. It’s therefore important that your dog’s parasite control regime treats roundworms, tapeworms and lungworm. Often, ‘standard’ treatments used by owners won’t cover all parasites - lungworm is very often overlooked.
By contacting your vet, you’ll be able to put together a comprehensive parasite control program to keep your pet and your family happy and healthy.