Ziggy (The Puppy Place #21) by Ellen Miles

The Petersons have become experts at fostering puppies until they can find them a perfect forever home. Charles brings home Ziggy, an adorable short-haired black and tan dachshund, from an overwhelmed owner at a local dog show. Ziggy is an active, curious little guy, who loves to explore. But when Ziggy manages to dig a hole under the backyard fence, his curiosity leads him into trouble. The Petersons have never lost a dog that they were fostering before! How will they find Ziggy? Where did he go?