Lumps of palm oil have been washed up along the north-east coast of England.
Residents carrying out a daily plastic collection on the beach at Whitley Bay found the white "crumbly and greasy" lumps.
The animal charity the PDSA has warned it is toxic to dogs.
"If a dog has eaten the bacteria-laden palm oil, the symptoms will develop within 15 minutes of eating it and sickness is the most common sign," it said.
The charity advised owners to "contact your vet immediately" if this happens.
There have been reports of palm oil being washed ashore on beaches in Pembrokeshire, Lancashire, Fylde and along the Northumberland coast.
The National Trust said it was still being found at Formby and along the Sefton Coast on Merseyside.
The RSPCA said lots of palm oil had washed up around the Wirral peninsula earlier in the month.