To quote Tom Waits:

“‘Rain dogs’ are dogs lost after the rain washes away the scent of home, thus barring their return…You know how after the rain you see all these dogs that seem lost, wandering around. The rain washes away all   their scent, their direction.”

“It’s like falling asleep somewhere and you thought you knew where you were and when you woke up…they changed all the furniture and the walls and windows and the sky turned a different color and you can never get back…”