"Dogs will start to pant heavily and their tongues will hang out and be a bright red color," Sarpong says. "They'll start seeking shade or the grass while they're walking."
Other cues include listlessness and convulsions, Davies adds.
FILE - In this July 13, 2017 file photo, a dog rests next to an air conditioner vent placed in a clothes shop during a hot summer day in Madrid. (AP Photo/Francisco Seco, File)
