Dog Aliens 2: Oreo (Dog Aliens Series)
Oreo is a rascal dog who loves to make trouble for his goody goody adopted brother Raffle, who keeps saying they're both aliens from outer space. Best if read after Dog Aliens 1: Raffle's Name. All the Dog Aliens stories have happy endings, and no dogs ever die in them (but wolves do).
Geared toward kids aged 9-12, but written with dog people of all ages in mind.