Round Rock police on Monday said the woman told investigators the collie mix named Ozzie was left in the vehicle -- with the windows rolled up -- for two hours.
Police say outside temperatures during Friday's incident were in the low 90s. The temperature inside the car was estimated at more than 140 degrees. Officials were unable to revive the animal.
Officer Dee Carver says the woman, whose name wasn't immediately released, told police that she didn't realize her dog could die under such conditions.
Carver says it's never a good idea to leave a child or an animal unattended in a vehicle.
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