At 1pm on Monday, January 11, a woman was walking her dog in Woodside when an "agitated" pit bull-type dog approached her and bit her dog, West Mercia Police said.
"Due to the dog's state the woman was fearful it would attack her," a statement said.
"The pit bull, which had black and white markings similar to a Dalmatian, appeared to be on its own without anyone in control of it.
"Officers are keen to identify the owner of the dog.
"Anyone who knows who the dog belongs to or has information about its whereabouts is asked to get in contact via the Tell Us About section of westmercia.police.uk or alternatively information can be passed anonymously to Crimestoppers on 0800 555 111."