There are several reasons why dogs can get diarrhea, ranging from mild to serious health issues. Here are some of the most common causes of diarrhea in dogs, according to the search results:

• Dietary indiscretion: Eating too much food, eating garbage, or eating spoiled food.
• Stress or anxiety: Stress, especially following travel, boarding, or other changes in the environment, can also cause acute diarrhea.
• Change in diet or treats: Switching to a new brand or flavor of food.
• Ingestion of foreign objects: Such as toys, bones, and fabric.
• Ingesting toxins or poisons: Including medications such as antibiotics.
• Parasites: Roundworms, hookworms, whipworms, Coccidia, or Giardia.
• Viral infections: Such as parvovirus, distemper, or coronavirus.
• Bacterial infections: Such as salmonella.
• Organ dysfunction: Or other systemic illnesses.
• Hormonal imbalances: And even some cancers.
• Kidney or liver disease: Which can cause diarrhea as a common symptom.

If your dog has just had one episode of diarrhea and is otherwise behaving normally, its usually not a cause for concern. However, if your dog has more than two episodes of diarrhea, or if the diarrhea persists for more than a day or two, its a good idea to call your veterinarian. Repeated bouts of diarrhea in a short period could indicate a serious health problem, especially if your dog is very old, very young, or has a compromised immune system.