The owner of a dog which attacked another dog in Redbourn is being urgently sought by police.
The incident resulted in a labrador being taken for veterinary treatment to its leg.
A spokeswoman for Herts Police explained that the attack occurred at 7.30am on Sunday May 11.
A man was walking his labrador in fields between the A5183 and Harpenden Lane when another dog, which was not on a lead, chased his pet and bit it, causing a serious injury.
The dog which attacked the labrador was described as a labrador-cross, with a square-shaped head. It was black with a white chest and about eight-to-nine years old.
Its owner left the fields with her dog, without leaving any contact details.
Police are appealing for witnesses and information in relation to the incident.
If anyone has details of what happened or knows the owner, please contact PC Capiciotto via the Herts Police non-emergency number 101.