Gastric outflow obstruction due to pyloric hypertrophy has been described as one cause of chronic vomiting in dogs. However, no reports were found with associated counter-clock partial gastric rotation. An 8-year-old male Shih-Tzu was admitted to this veterinary hospital because of chronic intermittent vomiting. A gastroscopy had been previously performed and revealed chronic gastritis and pyloric hypertrophy. Contrast radiographs after oral administration of barium sulphate suspension showed a delay of gastric emptying and also a counter-clock gastric partial rotation. Complete blood count and serum biochemistry demonstrated no abnormalities and the dog was submitted to surgery. At laparotomy a thickened region was palpated in the pyloric region and the stomach was filled with gas. A Heineke-Mikulicz pyloroplasty was performed by making a longitudinal incision in the serous and muscular layers of the ventral surface of the pylorus. The mucosal layer remained intact. With the help of traction sutures, the incision was sutured transversely in a simple interrupted one-layer pattern, using 3-0 absorbable suture material (Monocryl R). A Belt-loop gastropexy was also performed at the time of surgery by elevating a seromuscular flap in the gastric antrum and passing it beneath a tunnel created in the right abdominal wall. This procedure would prevent the partial rotation of the stomach, which contributes to the gastric outflow obstruction. The same absorbable suture material was used in the gastropexy, in a simple interrupted one-layer pattern. Oral ampicillin, omeprazole and Buscopan were recommended in the postoperative period and small amounts of paste diet many times a day were advised. The vomiting has ceased, the dog has recovered well and remained stable during the 6-months postoperative follow-up. This report showed that dogs with chronic vomiting caused by pyloric hypertrophy can become clinically normal following correct diagnosis and surgical correction. The seromuscular pyloroplasty was effective to treat pyloric hypertrophy in this case and there was no need of mucosal incision, which greatly minimized the risk of contamination. It is important to observe if the stomach remains in correct anatomical position. If any degree of gastric rotation occurs gastropexy may be necessary.