A 13-year-old female Labrador Retriever presented with chronic regurgitation. Radiography and computed tomography (CT) revealed nodules in the caudal esophagus. Upper gastrointestinal endoscopy followed by histopathological examination revealed esophageal granulomas caused by Spirocerca lupi. The infection was treated with milbemycin oxime. The therapy was successful, and a remarkable reduction in granulomas was observed. This case report describes the diagnostic imaging findings and treatment outcome of a dog with S. lupi infection in Japan.