Dog owners warned of deadly sea creatures washing up on beaches

Dog owners are being warned about hundreds of potentially deadly sea creatures that are washing up along parts of the Western Australian coast.

Every year between January and March, thousands of sea hares, or sea slugs, line the shores of several beaches southwest of the state, with sightings already reported around Augusta and Margaret River.

The slug-like creatures are dark purple or green in colour and can be the size of a football. They release a purple dye, much like a squid, and can be extremely harmful to pets.

Sea hares (pictured) are washing up on Western Australian beaches around the Augusta and Margaret River area.
The sea hares, or sea slugs, can cause overheating and seizures in dogs and are potentially deadly. Source: Facebook

Perth local Max Beckerling suspects a sea hare caused his four-month-old labrador, Ned, to die after a trip to a beach near Capel in the state’s South West with his family in 2018.

"We walked back from the beach and we washed the dogs and put them on the verandah to dry. There was nothing to suggest Ned was unwell," he told Yahoo News Australia.

But within 45 minutes, Mr Beckerling saw the pup lying lifeless on the floor.

"I thought he was sleeping," he revealed. "But he was dead."

Sea hares have a life cycle of one year, Dr Lisa Kirkendale, head of aquatic zoology at the Western Australian Museum, told the ABC and when dead, they wash up onto the shore.

But even then they're toxic to dogs, and can cause seizures and overheating if ingested.

"We have treated one toxicity this year but would expect about five or six for the season unless public awareness increases," Margaret River veterinary surgeon Dr Amy Forsythe told Yahoo News Australia.

"They've just started washing up in large numbers now but we're seeing more and more every year."

Mr Beckerling said he had never heard of sea hares and he didn't know what they were.

And while he did see some the day his beloved Ned died, he didn't see the pup go near them.

Speaking with Perth Now at the time, Mr Beckerling described the traumatic event as "harrowing and horrible".

"He was a beautiful puppy, so full of beans one minute," he said.

"Then next he wasn’t with us anymore."

A beach covered in sea hares. Vets are warning dog owners about the dangers of these creatures.
Sea hares have a lifespan of one year and wash up on beaches when they're dead. Source: Facebook

'Timely intervention is key to a positive outcome'

Professor Culum Brown, from Macquarie University, explained sea hares derived their toxicity from the algae they grazed on.

"They are only harmful if you eat them, and even then only some of the time," he told Yahoo News Australia.

"People don't munch on them but occasionally a dog might try should it find one washed up on the beach. If the individual hare has been eating particular types of algae it may cause harm to the dog."

"Timely intervention is key to a positive outcome," Dr Forsythe said.

And luckily for her, all of the cases she had treated had "been successful with prompt treatment", which can range from medical management to more intensive anaesthesia and gastric lavage (pump stomach).

A warning for dog owners

Posting on their Facebook page, Margaret River veterinary hospital, where Dr Forsythe works, warned dog owners what to look out for, and what to do if their pup comes in contact with one.

"Symptoms of sea hare toxicity include increased excitement, inability to walk properly, tremoring, vomiting, lethargy, seizures and eventually death," the post reads.

"These signs can show minutes to hours after ingestion or mouthing the sea hare."

Other beachgoers have taken to Facebook over the past few weeks to warn pet owners about sightings along the coast.

"Sea hare/slug on the beach at Back Beach, be careful with your doggies," one person said.

Others said they were also seen around the Geraldton area as well as Back Beach in the Bunbury region of Western Australia.

If you suspect your dog has eaten a sea hare it's recommended you contact your nearest vet immediately.

Do you have a story tip? Email:

You can also follow us on Facebook, Instagram, TikTok and Twitter and download the Yahoo News app from the App Store or Google Play.