Organisers of an annual horse festival in Japan where riders dressed as samurai re-enact battles said Tuesday they were considering changing dates for the gathering next year, after sunstroke affected 111 animals, killing two of them.At least 111 horses -- and dozens of people -- needed treatment for sunstroke at the Soma Nomaoi festival in Fukushima prefecture from July 29 to 31, after temperatures touched 35 degrees, the hottest in five years, organisers said.