Dogs' diarrhea may not necessarily heal on their own. It depends on the specific reasons for the dog's diarrhea:

1. If the diarrhea is only caused by a cold and the symptoms are relatively mild, then the dog can Self-healing.

2. If diarrhea is caused by viral infection or gastrointestinal disease, it will not heal on its own and needs timely treatment to avoid affecting the dog's health. If the dog continues to have diarrhea or is accompanied by symptoms such as depression and abnormal body temperature, it is necessary to consider the cause of parasite or viral infection.

3. If the dog has diarrhea caused by eating unclean food or indigestion, and the symptoms are relatively mild, the dog can recover on its own. The owner should fast the dog and provide proper hydration during this period.

There are some ways to prevent diarrhea in dogs:

1. Pay attention to keeping the dog warm at ordinary times, and do not let the dog sleep directly on the ground, especially in winter.

2. Pay attention to food hygiene and do not give your dog random food, especially chocolate, chicken bones, grapes, onions, etc.

3. Deworm your dog promptly.