WAIPIO VALLEY, BIG ISLAND (HawaiiNewsNow) - When a wild horse wandered onto Big Island taro farmer Brad Mock Chew's property in Waipio Valley, he was shocked by what he saw.
The animal could barely walk.
"Their back hooves are splayed almost like a crab," Chew said. "Just for them to get up and move it takes a lot of effort."
Nicole Olival of horseback riding tour company Waipio on Horseback said several wild horses in the valley have shown the same symptoms.
"It's obvious that there's something wrong with them. It's very clear that they're sick. It's heartbreaking," she said.
In the past few weeks, a handful of wild horses were even found dead.
"We have had a horse that died within immediate proximity of our property," said Noland Eskaran of the Waipio Taro Farmers Association. "There was at least three horse deaths that I was made aware of."
Horseback tour operators and others who frequent Waipio Valley called Kellyerin Claybaugh, a veterinarian with Aramat Equine Services.
Claybaugh conducted blood tests and ruled out neurologic Rhino virus, West Nile and influenza, but more testing is still needed.
"She said that tissue samples from a freshly deceased horse would help her determine what was going on a little bit faster," Olival said.
In a video Claybaugh posted on YouTube, she said the sickness may be caused by something the wild horses are eating.
Hawaii County Council chair Valerie Poindexter said she will call a meeting of county and state officials to offer assistance in determining what's causing the illness.
"It looks like it's a painful, slow death. The uncertainty or the unknown is what's causing the fear," Claybaugh said.
There's also concern that the condition might spread to domestic horses and other animals.
"So far none of the horses from either tour companies, or the mules that are down there have been affected," Olival said.
Scores of wild horses roam Waipio Valley. it's unknown exactly how many may have come down with the mysterious illness.