A dog with a runny nose, no food, and no energy may be caused by a cold. If the dog also has vomiting, diarrhea, blood in the stool, etc., it may also be parvovirus, and the dog needs to be checked at the hospital. Dogs are more likely to catch cold when the seasons change, so keep warm. If you catch a cold, you can take dog-specific cold medicine, and it will recover in a few days.