Two men were injured and three horses died after a trailer carrying 10 of the animals overturned on the A303 eastbound carriageway, after colliding with a lorry.
Seven were sedated and removed by vets and expert animal rescuers but one was killed in the crash and two had to be put down.
Hampshire Fire and Rescue Service said the drivers of both vehicles were not seriously hurt.
More top news
Philippa has the latest weather for the east
Philippa has the latest weather for the west
Nazanin Zaghari-Ratcliffe's five-year jail sentence is confirmed despite her husband's campaign to bring her home.