What causes a dog to have a swollen stomach and hard to breath?

A swollen stomach in a dog, accompanied by difficulty breathing, can indicate a serious condition such as gastric dilatation-volvulus (GDV), commonly known as bloat. This occurs when the stomach fills with gas and twists, leading to pressure on the diaphragm and impairing breathing. Other potential causes could include abdominal tumors, Heart disease, or fluid accumulation in the abdomen. Immediate veterinary attention is crucial, as these conditions can be life-threatening.