Jennifer Berry arrives at the Maricopa County Animal Shelter filled with dread. It is August and, even at 8:30 in the morning, the temperatures are close to 100. She opens the door of her van and, as she steps out, is hit by the heat like the blast from an oven door. Her thoughts go immediately to the dogs and cats inside the shelter. If it’s hot outside, it means the animals are hot too. If it’s cold, so are they. And if there was a thunderstorm the night before, she knows the animals will have been terrified the entire night, with no one to comfort them.

She looks at the building in front of her. A sprawling, one-story cement structure painted surprisingly cheerful oranges and blues. Lining out the door are people with dogs panting on leashes or cats meowing in cages. She does not know whether the people…