Are Slugs Poisonous to Dogs? (What Happens if a Dog Eats a Slug)

are slugs poisonous to dogs when eaten

At this time of year we get so many slugs in our garden; they love our plants. Unfortunately, our Frenchie Claude is very inquisitive and puts his nose into leaves and puddles and is frequently exposed to slugs and their slime… in fact, I even caught him licking a slug once.

But just how dangerous are slugs and slug slime to dogs? Can dogs die eating slugs or become in close contact to them? I decided to find out and research the dangers.

Are slugs poisonous to dogs? If eaten, slugs can be harmful to dogs due to a parasite they carry that causes lungworm in dogs. However, most common garden slugs are not actually toxic to dogs if eaten, but this does raise the risk of lungworm. There are also varieties of sea slugs that can kill dogs when ingested.  

What is the lungworm parasite?

Lungworms are tiny parasitic worms that can infect dogs, leading to a range of serious health issues including heart problems, breathing problems, and haemorrhaging. Haemorrhages can occur in the dog’s eyes, intestine, lungs, liver, and spine.

In simple terms; if your dog gets infected with a lungworm the effects can be catastrophic, and eating slugs is one of the highest risk activities leading to parasitical infection.

Symptoms of lungworm

Some types of dog are more prone to contracting lungworm. This include younger dogs and puppies (most likely due to being inquisitive), and the spaniel breed. The reasons for spaniels being more at risk of harm is not completely understood but could be a breed defect genetic.

Here are some possible signs to look out for:

  • Anaemia
  • Behavioural changes
  • Breathing difficulties
  • Coughing (plus coughing up blood)
  • Diarrhoea
  • Loss of appetite
  • Nose bleeds
  • Red eyes
  • Seizures
  • Tiring easily
  • Vomiting
  • Weight loss

The symptoms are easily misunderstood too, as they can be easily confused with other illnesses. Because of this it’s important you always seek your vet’s advice if your dog eats a slug, or you believe they have licked slug slime trails – the larvae can be infectious for up to 15 days after being left in slime.

Treatment for lungworm

If your dog or puppy does eat a slug and they contract lungworm, there are treatments available and most dogs will recover, providing it has been diagnosed early enough. Treatment doesn’t involve surgery, but instead medicines that will kill off the lungworm parasites.

are slugs toxic to dogs
You can see why an inquisitive puppy might eat a slug or even lick the slime.

Prevention is far better than cure though so take care to not let your dog drink from puddles, eat slugs, or lick the slime. Lungworm is also passed through dog faeces, so clean up after your dog, and also keep up to date with their spot-on worm and flea treatments.

Can dogs eat slugs?

Dogs can eat slugs, and some do eat slugs. Whilst slugs taste and smell nasty, this doesn’t seem to put some dogs off. But it’s a habit you need to help them break and completely avoid.

Why some dogs like to eat slugs is unknown. The most likely thing is that a dog might think its food due to the consistency or the curiosity of putting something unusual in their mouths.

What happens if a dog eats a slug?

Eating slugs can hurt your dog for two reasons;

  1. Whilst not toxic, the slug and slime will react badly with your dog’s digestive system leading to vomiting and possible diarrhoea.
  2. In worst case scenarios your dog could develop lungworm, and could even die due to the infection.

How do dogs catch lungworm?

Slugs are most common during the wetter months of the year. In the UK it tends to be the in the springtime.

If your dog is like ours, he will love jumping in leaves, rolling in mud, and running through puddles – all of which are prime activities that put them at risk of lungworm.

Yes, you read that right.

Your dog doesn’t actually have to eat a slug to get ill. The lungworm parasite can be passed to your dog from drinking rainwater, eating grass, licking the slug trails, dog faeces, or even sniffing the lungworm larvae up their nose.

Is slug slime poisonous to dogs?

Just like slugs themselves, the actual slug slime is not poisonous to dogs. However, slug slime can be harmful to dogs if it contains the lungworm parasite as it can lead to a dangerous infection.

So, the slug slime isn’t toxic, but it can be dangerous if lungworm parasite larvae are in it.

Handy Hint: Other dangers also lurk outdoors such as bees and wasps. But can bee stings kill dogs? I found out. 

Are all slugs poisonous to dogs?

As I’ve established, my research found that common garden slugs you find in your yard are not poisonous or toxic to dogs. But the parasites present in the slugs can be.

Based on that, if you were to ask me any of the following questions…

  • Are black slugs poisonous to dogs?
  • Are leopard slugs poisonous to dogs?
  • Are banana slugs poisonous to dogs?
  • Are garden slugs poisonous to dogs?

The answer to all of those queries will be no, they aren’t toxic. But, as I keep re-iterating, they can be dangerous.

There is a caveat to this, and that’s sea slugs.

Are sea slugs poisonous to dogs?

As a very broad generalization, most sea slugs are not poisonous to dogs, but some varieties will be toxic. Whilst the most common sea slugs should not be considered harmful, you still should not let your dog eat or lick one; they still may get ill.

The sea slugs that are known to be toxic to dogs are sea hares, Pleurobranchaea maculates, and some Nudibranch varieties found in Australia and New Zealand. You can read more about these in the following section.

Are sea hares poisonous to dogs?

Sea hares might look like sea slugs, but they are actually snails. You can’t see their shell, because it’s actually internal! These marine snails are common in shallow water in places such as California in the US and Perth in Australia – and even the UK.

The sea hare has a toxic purple ink or slime that is not toxic to humans but is poisonous to dogs. Sea hare toxicity to dogs is extremely high so you should not let your dog lick, eat, or get too close to them.

sea hare out of water
This is a sea hare out of water. They have been known to be toxic to dogs, causing fatalities. Image copyright M. Paradiz of Wikipedia.

I found a forum post from a vet who said this about sea hares and dogs;

“If you believe your dog has licked a sea hare, they can become ill very quickly. Look out for excessive drooling, possible seizures or muscle spasms, and throwing up. Sea hare poisoning can be fatal to your dog.”

Country by country toxicity differences

What I also did was look at English-speaking countries from around the world to see if there were any slugs or sea slugs native to those geographies that could be toxic. It made for interesting reading, but it was hard to find definitive information.

Here are the slugs that could be poisonous to dogs in Australia, Canada, New Zealand, United Kingdom and the United States.

Australia & New Zealand

According to The National Geographic, “Australia is home to some of the most bizarre-looking slugs on Earth”. The article listed 8 of the most unusual slugs in the region, and I discovered that three of them could be potentially harmful to your dog.

1. Nudibranchs

Some Nudibranchs are sea slugs whereas others can be found on land, albeit near the water, typically around coral and rocks.

According to the National Geographic article, Nudibranch slugs will warn off predators with a toxic and foul taste if eaten. But not all of them do. Some Nudibranch slugs pretend to be poisonous due to the bright colors they exhibit.

The bottom line is, don’t let your dog eat one as he will probably will become ill.

2. Elysia sea slug

Similarly, to the Nudibranch, the Elysia sea slug will also ward off predators with a toxic bacterium. I cannot find any evidence that it would be enough to kill a dog, but the Science Daily website did report this in 2019:

“The sea slug Elysia fights predators by wielding toxic chemicals that it acquires from eating algae. A team has discovered that these chemicals are made by bacteria living inside the algae, highlighting a surprising three-way dependence among sea slugs, algae and bacteria.”

3. Pleurobranchaea maculate sea slug

There is one sea slug found in New Zealand that is known to be extremely toxic to humans and dogs; the Pleurobranchaea maculate. This sea slug was linked to two dog fatalities in Auckland, New Zealand in 2009.

Professor Battershill of the Coastal Marine Field Centre in Tauranga was interviewed by the New Zealand Herald paper, and said:

“Due to warmer weather these toxic slugs can sometimes lose their grip from rocks in shallow tidal areas and end up being washed on to the shoreline… the toxic grey side-gilled slugs look like a little grey mouse, but with a sting in its tail. They are deadly because their skin contains the toxin Tetrodotoxin (TTX) which was the same toxin as the puffer fish.”

TTX is a potent neurotoxin that can kill when ingested by dogs. The NIWA website explain that a “lethal dose of TTX to humans is 1–2 mg. A human would need to eat 2.6 grams of sea slug in order to get a dose of 1mg of TTX” to die. That’s not a lot; just less than half a teaspoon, so you it wouldn’t even need that much to kill a dog.

If your dog has eaten a sea slug in New Zealand, I would recommend you seek vet advice as soon as possible. Poisoning symptoms include nausea and paralysis.

United States & Canada

Giant garden slugs can carry the lungworm parasite that is dangerous to dogs and can even result in meningitis to humans (see source) if ingested. However, there are no known slug species that carry poisons as such.

But certain sea slugs can be toxic to dogs as discussed earlier in this guide.

United Kingdom

Whilst there is no slug that could be considered toxic to dogs in the UK, common garden slugs and their slime trails can all carry the risk of having the parasite in them that could cause lungworm.

However, just like the rest of the world there are also certain sea slugs that carry toxic ink that should be avoided.

Handy Hint: What if you find slugs in your dog’s poop? What does this mean? I put all the myths to the test and can bring you the facts of the matter.

What to do when a dog eats a slug

If a dog eats a slug, you should not get into a huge panic. Yes, there are risks of lungworm, or poisoning if it’s certain sea slugs, but it is still relatively rare.

For example, in Scotland in 2009, lungworm was found in only 6.7% of slugs tested for the parasite. You can read more about the studies on the Vet Times website.

However, you should always go to the vet to be checked-up, even if they don’t appear to be ill or suffering. Lungworm in particular can take a few months before the signs set in.

If you live in the UK, there’s an interactive map available on the Bayer website. You can type your post code or location in and see how many lungworm cases have been reported in your area – access the lungworm map here – you can see an example of how it works below.

lungworm map
Slugs are poisonous to dogs in the UK, but only if your dog gets infected with lungworm. Here’s how many cases were reporting in the south east of the UK area this year.

The dangers of slug pellets

If you do decide the risk is too much to take, you might consider using pellets to rid your garden or yard of slugs. However, the majority of slug pellets have metaldehyde in them which is highly toxic to dogs.

Instead you might want to try some organic alternatives to slug pellets including:

  • Ground coffee
  • Beer traps
  • Egg shells and seashells
  • Diatomaceous earth
  • Copper tape
  • Slug repelling plants
  • Recycled wool paste pellets
  • Nematodes
  • Wheat or corn bran

Buy organic or dog-friendly slug pellets

For the best results I recommend buying dog-friendly slug pellets. Go to Amazon and do a search for organic slug pellets and you should be able to find something; I’ve made a quick Amazon link for you.

Conclusion

Whilst most garden and earth-dwelling slugs are not poisonous to dogs, they can be harmful if infected with the lungworm parasite. However, infection is rare and will often depend on where you live.

But lungworm infection can be fatal if not caught early, so it’s imperative you talk with your vet even if you have a suspicion of infection.

So, whilst they slugs are not toxic to dogs, they can certainly be harmful. It’s also worth noting that even if a dog doesn’t contract an infection, it can vomit once the slug hits the stomach – as a natural reaction more than anything else.

Disclaimer: I am not a vet, but all of the advice in this guide has been developed after doing my own research online. You should always consult with your vet after your dog eats something he shouldn’t. 

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If you are interested in keeping your dog safe from harm, please take a look at these other guides I’ve researched and published.

Marc Aaron

I write about the things I've learned about owning a dog, the adventures we have, and any advice and tips I've picked up along the way.

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