A Labrador running loose on the M56 caused a crash after a driver braked sharply to avoid hitting it.
The entire eastbound carriageway was briefly closed after the collision near junction 10 on Monday (April 11).
Reports of an animal on the section of the motorway emerged at about 12.30pm.
A Cheshire Police spokeswoman said the two cars crashed together after the vehicle in front braked to avoid hitting the dog.
No drivers or passengers were hurt.
The carriageway heading towards Manchester was shut off to traffic for about 15 minutes while the cars were moved to the hard shoulder.
Police have launched a search to track down the owner of the female black Labrador, which is about two years old and not microchipped, so it can be returned to its family.
Officers from the force's dog unit have taken her to the vets to be treated.
Anyone with information can contact Cheshire Police on 101 quoting incident number 322 of 11 April 2016.
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