Hy-Vee and Heartland Hospital placed the signs in the parking lots.
The animal shelter says more animals get left behind at hospitals, and they hope these signs will change that.
"We had the signs made because we want people who are parking their cars, and going on in for just a couple a minute, to remember that even in a couple of minutes, it can get really really hot inside your car, and be fatal to you dog, or to your child," said Kappy Hodges.
"If we can just get one person, if people can pay attention and stop and think, and if we get a couple people here and there to not do this, we've won the battle," said Brad McAnally.
The animal shelter encourages anyone to call them immediately, is an animal is left behind, with the car, license plate number and the location of the car in the parking lot.