A motorcyclist was killed after police reopened the road having failed to find a New Forest pony that was loose on a busy duel carriageway, an inquest heard.
Daniel Robins was one of two riders who were in collision with the animal on the westbound A31 at Picket Post near Ringwood.
The 31-year-old from Bournemouth was pronounced dead at the Royal Bournemouth Hospital.
Southampton Coroners Court heard this morning how police initially closed the entire A31 after the wild horse was spotted by PC Kevin Pearson.
Giving evidence, PC Pearson said having first seen the brown horse he lost sight of the animal because it was dark and he assumed it had gone into undergrowth.
He told the court there was on opening in the verge fencing after possible vandalism.
Meanwhile, with both lanes shut just after 5pm, rush hour traffic was building up as police officers struggled to locate the horse.
A police helicopter was requested but the control room did not call for one, the inquest was told.
After 40 minutes, the court heard, police decided to reopen the outer lane of the dual carriageway while shutting off the inner road for half a mile to enable officers to continue the search.
PC Pearson said: "Unfortunately we had to make a decision. We had to make a decision to allow traffic to flow. We could not keep the road closed indefinitely."
But unbeknown to the police officers the horse had strayed further than the coned off area, the inquest heard.
In fact the court was told that the horse was in the middle of the road some 1.1mile from the end of the closed off lane where officers were searching.
Before the collision at about 6.15pm on January 22, Mr Robins and the other rider Ian Woolgar, 47, from Broadstone, had ridden to the front of the stopped traffic.
When the outer lane was reopened the two set off, with Mr Robins ahead.
Within a couple of minutes of the road opening, Mr Robins then struck the horse which was standing in the centre of the road. This flung the animal into the path of Mr Woolgar who also hit it.
The probe also looked at both bikes and there were no defects and the weather and road conditions were good.
Mr Robins had no drugs or alcohol in his blood stream.
It was unclear whether he had his full beam on, although it was switched on after the impact.
Members of the public and then PC Rebecca Stark, the first officer on the scene, then tried in vain to revive Mr Robins.
PC Stark said she had spoken to Mr Robins just minutes before at the top of the road block warning him of a horse in the road.
The investigation could not determined the speed he was travelling.
A post mortem found he died from multiple injuries to the body and the head.
Mr Woolgar suffered broken bones and damaged liver and kidney.
The inquest also heard from Mr Robin's mum, Lorna. She asked why the rolling road block had not been extended to five miles to allow for the animal roaming.
She said: "My son would be alive today if that happened.
"I know that horses can travel far."