Four dogs (case 1; 2-year-old spayed female Schnauzer, case 2; 3-year-old spayed female Cocker Spaniel, case 3; 9-year-old castrated male Yorkshire Terrier, and case 4; 9-year-old intact female Shih-tzu) were referred to us with gastrointestinal signs such as diarrhea, vomiting, and anorexia. Results of blood analysis revealed hypoproteinemia and hypoalbuminemia in all dogs. Case 4 showed large circular mass which is connected with small intestine on abdominal ultrasonography and other 3 cases showed no remarkable findings on abdominal radiography and ultrasonography. We performed enterectomy in case 4 and gastrointestinal endoscopic examination with biopsy in other 3 patients. Finally, 4 patients diagnosed to protein losing enteropathy with 4 different etiologies.