"Hank the Cowdog: The Case of the Hooking Bull" by John Erickson (Book 18)

Olé...oh no! When Sally May and Loper head out of town for a wedding, Hank the Cowdog, Head of Ranch Security, knows it's up to him to keep things under control. After subjecting strawberry ice cream to rigorous product testing, test-driving a mysterious spaceship, and thwarting a sneak attack from a couch monster, Hank faces the fight of his life. A vicious hooking bull is terrorizing the north pasture, and he doesn't take orders from cowboys or cowdogs. In fact, he delights in thrashing them. Can Hank and Slim prevail in the face of overwhelming odds?