A female lurcher has survived falling out theback of a horsebox travelling at more than 70 mph on the M56 nearAltrincham.
She was narrowly missed by several cars beforedragging herself onto the grass verge.
A witness said the driver of the van pulling the horsebox stopped, cameback for the dog but abandoned her when she snarled at him.
The witness then called the RSPCA and the Highways Agency.
RSPCA animal welfare officer Katie Glenn was called to the scene. She said: "In my head I’m thinking 'this dog is going to be close todeath' but by the time I got there she was still fighting.”
A vet gave the lurcher, who is thought to be between two and three years old, given painkillers and a sedative before she was moved.
Although she had several abrasions and cuts,the only broken bone was her pelvis, which was fractured in three places.
The RSPCA’s Altrincham branch paid the £600 costof her operation and she is now being cared for by them.
They are trying to trace the owner of the van and have asked the Highways Agency to look over CCTV from the time. The witness described the van pulling the trailer as a white Mitsubishi 4X4 with a cab and flatbed at the back.
The incident took place between junctions 7-8 on theeastbound carriageway on Tuesday.
Anyone with information should call Katie Glenn on 0300 123 8018.