This is a potentially life-threatening situation. Watch your pet closely for signs of shock and consult your vet. Heat stroke risks. It does not have to be a hot day for your dog to suffer heat stroke. Even on a mild day, the temperature in a car can quickly soar to more than 100 degrees.
Heat stroke is a threat that too many pet owners underestimate.
If you go shopping in hot weather, leave your dog at home. Remember that the sun moves. If you leave your dog tied up in the shade, by afternoon he could be in the direct sun. Having a doghouse is no solution. If it's not in the shade, temperatures inside will be much warmer than the yard.