There could be any number of reasons that your dog loses its appetite and usually they are health related. Various illnesses or physical discomfort are the most common reason that your dog won’t eat. In fact, loss of appetite is one of the most common symptoms associated with medical problems in dogs. As such, it’s not always easy to understand the causes behind your dog’s loss of appetite.

Indeed, even slight discomfort or an upset stomach may cause your dog to stop eating. Plus, every dog will behave differently as some dogs will eat regardless of illness. Nevertheless, the first and most common reason that dogs won’t eat is because of problems with digestion. Just as in humans, upset stomachs may be the result of eating a new food or a non-food item. Otherwise, chronic problems like stomach ulcers can also affect your dog’s appetite. When your dog stops eating, try to identify other symptoms of digestive problems like vomiting, diarrhea, flatulence, and burping. Should any of these symptoms or the lack of appetite continue for more than 24 hours, visit your veterinarian immediately.
Other common causes of not eating include:

• Viral or Bacterial Infection
• Pancreatitis
• Dental disease
• Trauma or injury
• Intestinal obstruction

While a loss of appetite is often one of the first signs of illness in your dog, there are other effects associated with not eating. Dogs that are not eating may also stop drinking and dehydration becomes a serious concern. In fact, dehydration can lead to organ failure so it’s very important to have a veterinarian examine your dog for illness. Not eating can also lead to nausea and vomiting which can exacerbate the effects of dehydration. Again, if your dog stops eating for 24 hours, visit your veterinarian immediately.