Abstract: A 12-year-old male Pomeranian had a cough for nearly one year, and had symptoms such as worsening coughing and shortness of breath 1 week before the treatment. In order to diagnose and treat the dog, medical history inquiry, clinical examination, laboratory examination, imaging, echocardiography and electrocardiogram and other methods were used for the diagnosis, and treatment was carried out based on the diagnosis. The results showed that the dog showed shortness of breath and a heart murmur on auscultation; X-ray examination showed that the contact surface between the heart and the sternum increased, the heart shadow increased, the conicity value increased, and the heart was in an inverted "D" shape; two-dimensional heartbeat ultrasound showed that the right atrium was dilated, the left ventricular diameter was decreased, and the ventricular septal myocardium was thickened; Doppler echocardiography showed impaired diastolic function and right ventricular hypertrophy; color spectrum Doppler assessment showed tricuspid regurgitation, with regurgitation rate of 3.88 m/s, and the pulmonary artery pressure of about 65 mmHg; the electrocardiogram showed arrhythmia and abnormal ventricular beats. The dog was diagnosed with moderate pulmonary hypertension secondary to tricuspid regurgitation and right atrium dilatation. After 3 days of symptomatic treatment, the dog got better, but the dog died in a return visit 6 months later. The results suggested that canine pulmonary hypertension can be diagnosed by clinical symptoms and imaging examinations, but there was currently no comprehensive treatment plan, and the prognosis needed to be cautious.