Abstract
The author found a tumor in the thoracic part of the esophagus in a 7-year-old female Yorkshire terrier. The dog vomited due to passage disturbance of food as the main sign, along with remarkable loss of weight. The tumor showed extensive growth in the thoracic part of the esophagus, extending from the inlet of the thorax to the basis cordis. By thoracicoraparotomy, the developmental site of the tumor in the esophagus was dilated on the both sides and the tumor grew on the sternal side compressing the trachea, resulting in remarkable deformity and stenosis. The dog died owing to dyspnea under the operation.
The esophageal tumor excised post mortem had a cauliflower like appearance and was histologically diagnosed as fibrosarcoma. It infiltrated into the muscularis externa and tumor cells often showed mitosis and atypia. The tumor was clinically considered malignant becaus of its rapid growth, but no metastasis could be detected in any other organs examined.
