Dublin trainer 'in shock' as video captures 17 horses galloping up road after breaking loose

All 17 returned to McAuley's yard in the Naul having been rounded up by locals, but two were put down on humane grounds after a veterinary inspection showed they had suffered "bad cuts which severed tendons" during the harrowing experience.

Frightening dashcam footage circulated on social media over the past 24 hours showing the horses – all wearing rugs after morning exercise – galloping dangerously against oncoming traffic.

McAuley, who was saddling a winner in Gowran Park at the same time, was left shaken by the incident but he told the Sunday World that there were no collisions with any people or any damage caused to vehicles.

"I can't get my head around how that many went for that distance and never came across anyone. I was devastated leaving Gowran but when I saw the video, I feared the worst. Imagine having to knock at someone's door and tried to apologise," a shellshocked McAuley said.

"They were going an unbelievable speed, just fresh and running with the herd. Some galloped for seven or eight kilometres and ended up in Garristown. How they ventured that distance and didn't come across someone I'll never know.

"Two were put down for humane reasons after suffering bad cuts which severed tendons. You'd imagine something would have met a catastrophic injury in the road but they all came back in. It's bad but it could have been so much worse."

McAuley is still unclear as to what "spooked" them enough to force their way through a gate and reported that the other 15 horses thankfully just came back with "nicks and cuts".

"Something must have spooked them. Some of those horses have been here two years and in the same paddock and there have never been any problems with them. It only takes one to knock a gate and they all follow. It was a frightening thing to look at," McAuley said.