Abstract
The authors encountered a 4-month-old, female Shiba dog weighing 4.0 kg, who had been exhibiting abdominal distension and increasing ascites for 2 months. She was brought for further examination and treatment with the chief complaints of ascites and dyspnoea during sleep. The dog was diagnosed with ascites caused by cor triatriatum dexter based on the physical and imaging findings. Under general anaesthesia, she was treated with hybrid balloon dilation under transoesophageal echocardiography guidance. Her postoperative recovery was quite rapid and uneventful. This method appears to be a useful, new, and less-invasive treatment option for cor triatriatum dexter.