A man was attacked by a dog and knocked off his feet as he worked in a garden in Gustard Wood, Wheathampstead.
The man was working on Tuesday, June 17, between 11.50am and 12.10pm when the dog, which he had seen previously and had no problem with, attacked him.
PCSO Paul Fletcher from the Harpenden and Rural Neighbourhood Team said: “We need to trace the owner of this dog and make sure he is not able to harm anyone else.
“The gardener had scratches on his arm where he tried to protect his face, but his injuries could have been a lot worse.”
The dog is described as a black and white border collie with a black face, white neck and white patches. He is about two feet high and does not wear a collar.
Police urge anyone with information to contact PCSO Fletcher on 101 quoting crime reference number F2/14/865.