What is your diagnosis? Gastroesophageal intussusception.

A 3-year-old sexually intact male Dogue de Bordeaux was evaluated because of respiratory distress. The patient had been admitted earlier at the referral clinic because of vomiting and regurgitation with subsequent development of dyspnea and cyanosis. The dog had a history of megaesophagus and renal disease, which had been diagnosed at 10 weeks of age. On initial evaluation, the dog was laterally recumbent. Physical examination revealed hypothermia, mild cyanosis, tacky mucous membranes with prolonged capillary refill time, and labored breathing. The lungs could be auscultated in all lung fields, and findings on abdominal palpation were unremarkable. Blood gas analysis revealed severe metabolic acidosis and a high lactate concentration. Measurements of PCV and serum total protein, blood glucose, and BUN concentrations revealed high serum total protein and BUN concentrations (PCV and blood glucose concentration were within reference ranges). Radiography of the thorax was performed (Figure 1).