In the opening scene where we see demolished homes and we see a dog running in the background, the trainers brought the dog out of the SUV and instructed dog with a toy to run from A to B. When filming began, she directed the dog verbally “this way” to start searching through the rubble as she walked along the cleared path between rubble piles. Dog searched back and forth through the piles, sniffing and jumping along the piles.
In the scene when there’s a welcome home party inside a house and we see a dog in the background, the trainers placed kibble on the kitchen floor and brought the dog to set. On action, the dog sniffed the ground and ate the food.