The 32-year-old model suffered severe whiplash when her Toyota jeep - which her boyfriend Leandro Penna was driving - collided with two runaway stallions and one of them smashed through the windscreen.
Both creatures, which had jumped a fence and bolted in front of the vehicle, died instantly and the 4x4 was declared a write-off.
A source told the Daily Mirror that the pair are lucky to be alive and Leandro's quick-thinking could have saved them.
They said: "Quite frankly, it beggars belief that Katie and Leo survived at all. And Katie knows just how close she came to dying.
"The two animals ploughed into their vehicle, with one flying through the windscreen, backside-first, hitting both Katie and Leo simultaneously.
"Luckily, Leandro reacted lightning-quick, braked hard and swerved violently the moment he saw the horses. Although it wasn't enough to save the horses, undoubtedly his reactions saved the pair's lives, plus those of the three passengers in the back.
"No matter how well you perform there's always somebody of intelligent opinion who thinks it's lousy." - Laurence Olivier
Ye gods...why I brake for large animals if I can (no, I will not hit the deer if there's any way at all to avoid it, no matter what my tailgater wants) and why I'd be terrified of my horse getting loose. How terrifying...