Police say an officer and his dog were bitten by a man resisting arrest in Kansas City.
Officer David Magruder tried to arrest the man, suspected of dodging a cab fare, early on Friday morning.
The man began to punch Mr Magruder, who then released police dog "Soty" from the patrol vehicle using a remote control, a local newspaper reported.
Soty bit the man, who then bit back, according to police, nearly taking off the dog's ear. He also bit Mr Magruder.
The fight is said to have finally ended when support officers arrived on the scene and used a Taser stun gun to subdue the suspect.
The dog's ear had to be stitched back on by a vet, but he has lost a small piece, according to the Kansas City Star newspaper, which carried the story.
Mr Magruder also received bite injuries and was treated in hospital.
"I've had people fight my dog before, but not bite him," Mr Magruder told the Kansas City Star.
The suspect has been charged with stealing, resisting arrest and assaulting a police officer.
http://news.bbc.co.uk/1/hi/world/americas/4009567.stm