Dogs of the Drowned City, book 1: The Storm
Dayna Lorentz2012

When a hurricane forces his family to evacuate without him, Shep the German Shepard is confused. Where is his boy? Will he ever return? And what will Shep do in the meantime, now that the extra bowls of food -- not to mention all those tasty things he found in the big cold box -- are gone?
Then another dog shows up at Shep's window and convinces him to escape. There's food outside, and a whole empty city to explore. Shep just wants to go home . . . but the adventure of a lifetime is just beginning.