A police officer and two other people were injured when a car collided with his dog van.
Northumbria Police said officers were looking for a Vauxhall Corsa involved in another crash in Sunderland on Sunday when the car hit the police van.
The injured officer has now been released from hospital. Two police dogs in the van were not seriously injured, the force said.
A 30-year-old man has been arrested in connection with the incident.
A police spokesman said officers went to the Hylton Road area after being told the Corsa was being driven on the wrong side of the road and had hit another vehicle.
It hit the police van in Mowbray Road during the search, the spokesman said.
The force later tweeted a picture of one of the dogs receiving "some much-needed TLC" after the collision.
Here's police puppy Kassey who is receiving some much-needed TLC following yesterday's collision on Mowbray Road, Sunderland. She'll be reunited with her handler later today.— Northumbria Police (@northumbriapol) December 31, 2018
We are still keen to hear from any witnesses to the collision. Please get in touch. #ProudToProtect pic.twitter.com/hZW1Vm37nJ