If your dog has a cold, fever, or has an infectious disease, or has symptoms such as diarrhea or vomiting, it will cause a loss of appetite. It is most likely a digestive organ disease, and heart disease can also cause a loss of appetite. .

If the dog is older, internal organ diseases such as uterus, liver and kidneys are generally considered. If it is an underage dog, it may be caused by infectious diseases such as parvovirus, bacterial gastroenteritis, or gastrointestinal discomfort caused by food irritation.

When a dog is anxious, it is very likely that it is not interested in any food. Another reason is that when a dog is in heat, it may also cause a loss of appetite.