Signs of Diarrhea in Dogs It is important to understand that diarrhea in dogs can take several forms. Stools can range from abnormally soft to watery. Other clinical signs may be present such as straining while defecating, gas, abnormal odor, or blood and mucous in the stool. Many cases of diarrhea are self-limiting, but others require treatment. Bloody diarrhea with severe straining may be an emergency especially for small dogs. Diarrhea along with vomiting can be signs of serious intestinal obstruction that may even need surgery. Weakness, pain, vomiting, or agitation are serious signs that the dog needs medical attention.