Waimate woman Robyn Cederman and her 15-year-old daughter Philippa had been driving south on State Highway 1, to ride the family horse on Waikouaiti Beach, when their vehicle, which was towing a horse float jackknifed north of Hampden.
Mrs Cederman said the float began to sway as they drove over a ridge, and then became uncontrollable as the horse tried to steady itself.
The car and float jackknifed and the float rolled on its side, throwing the 18-year-old Arabian-cross out of the horse box, across the road and down a bank.
Her daughter said a local farmer had helped volunteers from the Hampden Rural Fire Brigade move the trailer, and had allowed her to give the horse a run in his paddock.
Although she had a nervous wait to see if the horse, which was named Aslan, would be able to walk, it turned out that he was ''pretty tough'', she said.
''I was half expecting to have to put him down, but no, he's fine.''
Mrs Cederman added that Aslan would be ''rested and loved'', when they returned to Waimate.
Hampden Rural Fire Officer Graham Aston said no other vehicles had been involved in the incident, but both the Cedermans and the horse had been ''very lucky''.
State Highway 1 was closed for five minutes, following the incident, which happened about 11.45am on Saturday.
