Joker, a gelding, took less than 3 minutes to steer his rider and locate a volunteer carefully hidden on a 13-acre tract of land, The (Portland) Oregonian said Tuesday.
Jefferson County Sheriff Jim Adkins said the demonstration "definitely got my attention."
"That was a pretty difficult search because the wind kept changing on us," he said. "That horse just went right over there and zigged and zagged and zoomed right in."
Kate Beardsley and Laurie Adams, who organized the demonstration, said they've known for some time horses can act in much the same manner as bloodhounds, and have been practicing "equine air-scenting" -- training a horse to alert a rider when a certain scent is in the air.
The women say when horses get tired, they open their nostrils wider, exposing more olfactory nerve endings, whereas dogs pant their tongues, making them less likely to smell something.
Dogs are better at tracking scent on the ground but horses stand taller, making them more likely to smell something that wafted into the air.
"A lot of people don't know that horses do this at all," said Beardsley.
Adams said careful study can help identify when a horse is signaling a certain scent.
"This is so natural for a horse," Beardsley said. "Horses smell everything, and they tell everyone around them what they smell."