Police are trying to trace the owner of a dog that repeatedly bit a woman on the face and neck in a Hertfordshire park.
The victim was in Cherry Way Park, Hatfield, when a brindle Staffordshire Bull Terrier attacked her dog.
She fended it off but the dog then attacked her. A man jogged over and pulled the dog away.
Police have just released details of the incident on the evening of 3 August and said the woman may need surgery.
The dog is described as possibly crossed with a pit bull, and was the size of a Labrador, police said.
It had a white chest.
The man, who led the dog away after the attack 1945 BST, is described as 6ft (1.83m), with a slim build and aged in his mid 20s to early 30s.
He had dark brown, flat, short, hair and was wearing a black t-shirt and jeans.
He was with two other men.
Pc Kelly Bailey said: "Our investigations are ongoing to determine who the owner of this dog is and I would appeal to anyone who knows who he may be, or who may recognise the dog, to contact me as soon as possible."