When the Ghost Dog Howls is a novella written by R. L. Stine. It was first published in 2010 and was the thirteenth book in the Goosebumps HorrorLand book series.
Description[]
Twelve-year-olds Andy and Marnie had a great week in HorrorLand, even though they were freaked out by Murder the Clown and a zombie mob. When the park's Chiller House store offers Andy a free souvenir he doesn't ask any questions - despite the shopkeeper saying he'd have to pay "next time you see me"... or that the souvenir hound's tooth is said to be haunted. He thinks it's worth the risk to have a dog's tooth that grants wishes, but when he hears howling in the night and Marnie starts behaving oddly, she thinks again about the gift from HorrorLand.