A post on social media by Yorkshire Coast Pet Care, which went viral on Monday January 10, was shared to raise awareness of a number of dogs becoming ill after walking on Yorkshire Coast beaches.
In the 1,100 comments, several dog owners shared their own experiences of the unexplained illness.
Some of the symptoms dog owners claim their pets have include vomiting, diarrhoea and lethargy, lasting from a few days up to a week.
Yorkshire Coast Pet Care said it has been "inundated" with cases and advised owners to avoid the beaches until environmental health experts can figure out what is causing this illness.
Cath Baggins said her working cocker spaniel Roo became ill the day after visiting Fraisthorpe Beach, near Bridlington, on December 30.
Roo spent six nights at the vets, after prolonged vomiting and diarrhoea led to dehydration, but she is now recovering at home.
“We just went into panic mode, thinking she’d eaten something and it had poisoned her,” Ms Baggins said.
“I thought we might lose her because the vets couldn't tell us what was wrong and this diarrhoea just didn't stop.
“It (the beach) is my favourite place to go and it's my dog's favourite place to go, but I don't know if I'll dare go again.”
Veterinary nurse Brogan Proud said she works at practices across North Yorkshire and she has seen “tonnes” of dogs suffering with this mysterious illness.
She said: “I'm personally not taking my dog on the beach for the next couple of weeks and if your dog shows any symptoms of vomiting or diarrhoea I would get onto the vet straightaway.
“The sooner that they've had this injection that helps them stop vomiting, the sooner they can start getting better.”
Aldgate Veterinary Practice, which has sites in Bridlington and Driffield, say they have seen several dogs with vomiting and diarrhoea over recent days..
Giles Moore, a vet at Aldgate Veterinary Practice, said: “Given the reports circulating about this being a beach-related issue, it is a sensible precaution to monitor closely any dogs that have been to the beach.
“If they start with vomiting, the first thing to do is to withdraw food for 24 hours.
"If they continue to vomit or become lethargic then they should contact their local vet as soon as possible.
"If the vomiting settles, then they can start feeding bland food little and often and build back up to normal quantities over a period of a few days.”
He added: “If it’s just diarrhoea they can continue to feed their pet bland food like chicken and rice.
"As with the vomiting, if it’s not resolving or they become lethargic, then they should contact their vets as soon as possible.
“Water should be made available at all times to animals with gastrointestinal signs.
"If they cannot hold water, then they should contact their vets.”
In Scarborough, several dog owners claim they have visited North and South Bay, Peasholm Park, Burniston and Dalby Forest and their dogs have become ill.
In Bridlington, claims include North Beach, South Beach, Fraisthorpe Beach, and the cliff tops.
One Facebook user commented: “Our dog has had bad sickness and diarrhoea since new year following a trip to Bridlington and Flamborough.
"Vets treated him with antibiotics and anti sickness and luckily he’s on the mend.”
Owners also claim their pets have become ill after visiting Whitby beach, Robin Hood’s Bay, Runswick Bay and Stainsacre.
A Facebook user said: “We stayed in Robin Hood's Bay between Christmas and new year.
"My dog has been ill since, sickness and diarrhoea really bad. Only just starting to get better now”
Sue Beck, Practice Manager of Beck Veterinary Practice in Whitby, said: “We have had an increased number of pets that have been in with vomiting, and with vomiting and diarrhoea or just diarrhoea.
"We have had a number that haven’t needed to be on Intravenous Fluid Therapy, and some that have.
“I would say to owners, beware where you're taking your pets.
"It’s not only the beach, we have it in other areas, we’ve had it on the moors.
"Keep your dog on a lead so you can see whether they’re picking things up that they shouldn’t and if they are ill, contact your local vet.”
An investigation was launched in October, after dead crabs, lobsters and fish washed up along the North East coast.
Thousands were found on beaches in Hartlepool, Redcar, Saltburn, Staithes and Whitby in October, but the Environment Agency said they were not killed by pollution.