Abstract
Gastrointestinal stromal tumors (GISTs) of cecum (case 1) and pylorus (case 2) were surgically removed and diagnosed in two dogs. Case 1 was clinically normal 10 months after surgery, whereas case 2 died of intraperitoneal metastasis 55 days after the operation. The percentage of cells that were Ki-67 positive were 4.4%(case 1) and 19.2%(case 2), and the mitosis index was 0.25% and 1.1%, respectively. The fact that case 1 had a favorable outcome while case 2 had a very poor result may suggest that canine GISTs have various outcomes. Ki-67 and mitosis index may be good prognostic factors for canine GISTs.
