A substance that is suspected to be palm oil has washed up on the beach near Lytham lifeboat station.
Fylde Council issued a warning to dog owners over the substance on social media today.
A spokesman said: "Please be wary when taking dogs on the beach and keep them on leads as much as possible."
Palm oil is attractive to dogs, and can cause vomiting, diarrhoea, kidney failure and liver damage if ingested.
Anybody who sees palm oil on the beach is asked to report it to Fylde Council by calling (01253) 658658 or emailing firstname.lastname@example.org.