Safety arrangements at New Zealand's answer to Spain's "Running of the Bulls" - the "Running of the Sheep" – are being reviewed after hundreds of the animals ran amok through Te Kuiti injuring a spectator on Saturday.

They leapt over barriers designed to keep them on the main street and protect 7000 spectators who turned up to watch the annual event.

All semblance of order completely broke down with the sheep crossing the main road and the rail track before heading into the hills.

One woman was taken to hospital after being knocked unconscious when she was bowled over by the frightened sheep.

The SPCA has concerns about the event and the stress it causes the sheep.

SPCA Auckland chief executive Bob Kerridge said his organisation opposes the event.

"Mercifully it is not done that often but the running of any animals out of their environment would naturally frighten them.

"What's the point? It's entertainment at the expense of the animal," Mr Kerridge said.

Only 400 of the nearly 1500 sheep let loose kept to the planned route and crossed a finish line helped by Prime Minister John Key.

Watch last year's sheep run below:

Watch last year's sheep run below:

Organiser John Fagan said he was sorry that the woman was injured.

"Obviously we do our best to see they don't."

He said the sheep run would be back next year subject to some changes.

"We plan to have the street wider at that end so the gap down the middle of the street is more inviting for the sheep to run down," he told 3News.