The Case of the Dog-Wrecking Horse (Hank the Cowdog #84) by John R. Erickson

Yard Rule No. 1: No Horses Allowed It's Slim's birthday, and the day is off to a great start when Miss Viola delivers a pan of fresh-made cinnamon rolls! However, a report comes in that a trash-talking, rule-breaking, daffodil-eating horse named Snips has invaded Sally May's yard, and Hank has to spring into action. When he appears on the scene, things go from bad to worse when Snips decides to hold his ground, resulting in a showdown that earns Hank a trip to the vet. Once in town, Hank decides to enjoy his trip to the big city and quickly winds up on the wrong side of some pretty tough local mutts. Will Hank ever make it back to his ranch?