A police officer and his dog were punched and kicked repeatedly after being called to deal with a fight at a Cambridgeshire pub.
Four men had attacked four members of staff at The George Hotel in the Market Place, Whittlesey, early on Sunday.
They were thrown out of the pub and followed by the officer and his dog.
The men were joined by a group of about 20 people and turned on the officer and his dog near AA Car Sales in Eastgate, police said.
They were kicked and punched until more police officers arrived and the crowd was dispersed and arrests made.
Neither the officer nor his dog was seriously hurt but the officer suffered cuts and bruises and needed time off to recover, police said.
Det Con Tade Toseland said: "This was a cowardly attack which involved a lot of people and I would like to speak to anyone who was in the area at the time.
"The officer and his dog are still recovering from the attack and they were left very shaken.
"I would urge anyone with information to get in touch."
Five men, aged 20, 22, 26, 42 and 51, have been arrested and bailed to return to March Police Station on 16 September.
A 15-year-old boy has been arrested and bailed to return to police on Tuesday.