It depends on the cause of cat diarrhea and whether the symptoms are severe to determine whether it can heal on its own. Generally, diarrhea caused by other diseases will not heal on its own. Common causes of cat diarrhea: 1. Indigestion 2. Weather changes 3. Colds 4. Infectious diseases, bacteria and viruses. If diarrhea is caused by indigestion and weather, it can be cured by itself. If it is caused by colds or feline plague, it cannot be cured by itself. You need to go to a pet hospital for treatment in time.