Cunningham said the horses were trapped in the float for around two hours.
"They were very quiet the whole time and luckily they had all managed to get back on their feet."
He was stunned that the horses survived the ordeal. At the very least he expected the horses might have suffered broken legs.
Vets expect the horses should be back racing in about a month.
For his part, Cunningham suffered a small cut to his leg and his passenger suffered a sprain.
The Massey University veterinary emergency response team sedated the horses as firefighters cut off the rear of the truck.
Response team leader Patrice Palleson-Putt said the removal of the horses went smoothly.
The Saddle Rd was closed for around 45 minutes while the horses were removed from the float and it was hoisted back on its wheels.
Traffic was heavy at the time.
The Massey response team used its own float to transport the animals back to Marton.
Cunningham had three horses racing in Palmerston North today (Friday) and had already been offered seven horse floats to get them there