Belterra also canceled 

https://paulickreport.com/horseplayers-category/heat-advisory-forces-racing-cancellations-at-horseshoe-indianapolis-oak-grove/

This heat wave sucks

Helpful info on heat and racing with horses

https://paulickreport.com/horse-care-category/handling-the-heat-racetrack-policy-and-running-during-the-dog-days-of-summer/

and this has more info

https://paulickreport.com/horse-care-category/cooling-out-on-the-track-science-says-you-may-be-doing-it-wrong/

Churchill cancels racing Thursday due to heat

https://www.thoroughbreddailynews.com/churchills-twilight-thursday-racing-cancelled-by-excessive-heat/

Not canceled, but will start earlier at Horseshoe Indy Wednesday 

https://paulickreport.com/horseplayers-category/extreme-heat-horseshoe-indianapolis-moves-up-wednesday-post-time/

Laurel cancels their Sunday card due to heat, and pushes back their start times Saturday .

Colonial Downs cancels their Saturday card.

(I don’t know why BH didn’t combine these 2 articles……)

https://www.bloodhorse.com/horse-racing/articles/261518/laurel-park-cancels-sunday-program-due-to-heat-forecast

https://www.bloodhorse.com/horse-racing/articles/261534/heat-cancels-colonial-racing-laurel-moves-post-times

Canterbury and Woodbine canceled racing today due to extreme temps

https://www.bloodhorse.com/horse-racing/articles/262022/woodbine-canterbury-park-cancel-aug-7-cards