The Isles of Scilly's vet has warned dog owners on the islands to steer clear of Porthloo slip on St Mary's.
Dr Heike Dorn said that she was contacted yesterday by residents of the area whose pet had stepped in something unpleasant during a walk.
She wrote on social media: "They informed me that one of their dogs, while on a morning walk, had trod on some horrible grey epoxy resin that appeared on the slip. It was setting on the dog's paws and they were very worried.
"To every dog owner: Avoid this area for the moment... although the Duchy put some sand on it it may reappear."
Advising anyone who has already encountered the substance, she said: "If your dog gets it on his paw remove it with acetone (nail varnish remover), then bathe the paws in mild shampoo and in the end massage it with some oil as the poor skin will be cracked and dry after the procedure!"
Photo by the National Oceanography Centre.