A dog that has not eaten and only drank water for five days can be a worrying situation. Here are some possible reasons and suggestions:

Health problems: Your dog may be sick, such as digestive problems, mouth pain, infection, etc. If the dog is accompanied by other abnormal symptoms, such as vomiting, diarrhea, lethargy, etc., it is recommended to take it to the veterinarian for examination and diagnosis as soon as possible.

Dietary problems: The dog may not be interested in or adapt to the current food. Try offering different foods, or consider changing dog food brands or flavors.

Environmental changes: Changes in the environment, such as moving, new members joining the family, etc., may have an impact on the dog's appetite. Try to create a quiet, familiar and comfortable environment for your dog.