Before Jessica and Simon MacLean adopted their rescue dog, Kristy, they made a list of traits they hoped to find in a dog, like “friendly” and “likes to play.” The foster family for the year-old Lab mix gave the thumbs-up, and Kristy arrived at their Brooklyn home in mid-September.

But during most of that first week, Kristy was hardly the “best friend” that their 10-year-old daughter, Bea, had been begging for. “She retreated to her crate at every opportunity. She didn’t even wag her tail,” Jessica MacLean says. “To be honest, we started to wonder if we’d made the wrong decision.”

Turns out, the MacLean’s experience is hardly unusual. Just like people, animals need time to adopt to new situations. “A dog’s