Two of the animals died, they said.
The annual three-day event, which features more than 400 participants dressed as medieval samurai warriors fighting on horseback over flags that are shot overhead by fireworks, attracted more than 120,000 people, reports said.
Yoshichika Hirata, a member of the festival’s executive committee, told AFP that changing the date of next year’s event to a cooler period would be discussed at a meeting on Thursday.
“We sprinkled water on the track for the first time, as extreme heat was expected. We used three water-sprinkler cars, but water dried up quickly,” Hirata said.
One horse died during last year’s festival, after which a majority of riders supported a plan to change the date, according to a survey done in December.