WAIPIO VALLEY, BIG ISLAND (HawaiiNewsNow) - A group of veterinarians hasn't been able to determine what killed 13 wild horses in Waipio Valley this summer.
The horses died in June and July, and were all among a single band that lives on the west side of the valley.
The state said vets did conclude that the horses didn't die from an infectious disease.
"The incident may be attributed to possible exposure to a toxicological event," a state Department of Agriculture news release said.
For more information on the investigation, including toxicology reports, click here.
About 60 wild horses live in Waipio Valley.
And over the summer, residents started to see concerning signs of illness in the animals: They were emaciated, struggling to walk and confused.
"This disease investigation into the cause of the deaths of these wild horses is one of the most extensive in Hawaii in my recollection," said Jason Moniz, manager of the Agriculture Department's Animal Disease Control Branch.
"In addition to the veterinarians, laboratories and researchers who worked on this case, we appreciate the help of Waipio Valley taro farmers who provided assistance, observations, information and feedback and who showed sincere concern for these horses."