Dogs with hard and distended stomachs generally consider gas. Dogs that have eaten too much easily fermented food can cause gas, which can compress the dog’s chest cavity and cause shortness of breath and mental distress. Fluid accumulation in the abdominal cavity can also cause the dog’s abdomen to increase in size. And dogs with tumors and ascites are also causes that can cause the dog’s belly to become hard, but this condition usually slowly makes the dog’s belly hard and large. However, the more common cause of a hard tummy in dogs is constipation, where hard stools stay in the dog’s intestines and the dog’s tummy becomes hard.
