The heat wave that swept across the U.S. this week broke temperature records and strained power grids as people cranked up the air conditioning in an attempt to keep cool. Horses also suffered in the extreme temperatures, prompting a shut-down at several tracks and stopping carriage rides in New York’s Central Park.

With searing heat and smothering humidity come special health concerns for horses. Phoebe Smith, DVM, Dipl. ACVIM, of Alamo Pintado Equine Medical Center, Los Olivos, Calif., reports that the center saw an unusually high number of colic, dehydration, and respiratory distress cases during the week of triple-digit temperatures in their normally cool valley.

On the other coast, Ray Sweeney VMD, Dipl. ACVIM, of the University of Pennsylvania’s New Bolton Center, reports seeing weanlings in respiratory distress due to heat.

“Any time it’s uncomfortable for people, that’s the time to be alert,” says Sweeney, who recommends paying special attention to weanlings already fighting pneumonia, geriatric horses, and any animals with a heavy hair coat, such as those with Cushings. Additionally, a horse that already has an elevated temperature due to an infection will be at additional risk in hot weather