Why is my dog not eating?

A decreased appetite in dogs has a broad range of potential causes. Some are relatively minor — stress from a new environment, a change in routine, or simply being picky about a new food. Other causes, however, reflect an underlying medical condition that requires attention.

Dental pain is one of the most common and overlooked causes of appetite loss. Broken teeth, advanced gum disease, oral tumors, and infections can make chewing painful enough that a dog avoids food even when hungry. Gastrointestinal conditions — including inflammatory bowel disease, pancreatitis, and intestinal obstructions — can also suppress appetite, often alongside other symptoms such as vomiting or diarrhea.

Systemic illnesses such as kidney disease, liver disease, cancer, and infections can cause a gradual or sudden loss of appetite. Certain medications, particularly chemotherapy drugs and some antibiotics, may also reduce appetite as a side effect. Identifying the specific cause is important because the appropriate response depends entirely on why the dog has stopped eating.

Dogs are often stoic about oral pain, and a broken or fractured tooth may go unnoticed until appetite changes become apparent. Advanced periodontal disease, which affects a large percentage of dogs over the age of three, can cause significant discomfort, loose teeth, and infection that extends below the gum line.

Signs of dental pain may include difficulty chewing, dropping food while eating, favoring one side of the mouth, drooling, bad breath, and reluctance to have the face or mouth touched. Some dogs will eat soft food but avoid kibble, while others may stop eating altogether.

A thorough oral examination — often performed under sedation for a complete evaluation — is the best way to identify dental problems. Treatment may include extractions, professional cleaning, or antibiotics for infection, and many dogs show significant improvement in appetite once oral pain is addressed.

Gastrointestinal (GI) disease is a broad category that includes conditions affecting the stomach, intestines, and associated organs. Inflammatory bowel disease, gastritis, enteritis, pancreatitis, and intestinal obstructions can all cause a dog to lose interest in food — often alongside other symptoms such as vomiting, diarrhea, abdominal pain, or weight loss.

A foreign body — a toy, bone, or other object lodged in the stomach or intestines — can cause complete appetite loss along with repeated vomiting and lethargy. This is a potentially serious condition that requires prompt evaluation and may need surgical intervention.

When GI disease is suspected, diagnostic testing typically includes blood work, fecal examination, and imaging with X-rays or ultrasound. These tools help identify the specific problem and guide appropriate treatment.

Several systemic illnesses can cause a dog to stop eating, sometimes before other symptoms are apparent. Kidney disease, for example, often causes nausea and appetite loss due to the buildup of toxins in the bloodstream. Dogs with kidney disease may also show increased thirst and urination, weight loss, and lethargy.

Liver disease can suppress appetite through nausea and metabolic changes. Pancreatitis — inflammation of the pancreas — often causes a sudden refusal to eat alongside vomiting, abdominal pain, and lethargy. Cancer, infections, and autoimmune conditions can also affect appetite through a variety of mechanisms.

Because systemic illness can develop gradually and initially present with appetite loss as the primary or only sign, blood work and other diagnostics are an important part of the evaluation. Early identification of these conditions generally leads to better treatment outcomes.

While skipping a single meal is not necessarily alarming, a dog that has not eaten for more than 24 hours should be evaluated by a veterinarian — particularly if the appetite loss is complete rather than partial. Prolonged anorexia can lead to hepatic lipidosis (fatty liver disease), muscle wasting, and weakened immune function, making the dog more vulnerable to complications.

Puppies are especially at risk because they have limited energy reserves and can become hypoglycemic (low blood sugar) quickly when not eating. Senior dogs with underlying conditions may deteriorate more rapidly when food intake drops. Both groups should be evaluated promptly when appetite loss is noticed.

The presence of other symptoms alongside appetite loss — such as vomiting, diarrhea, lethargy, pain, or behavioral changes — increases the urgency of the situation. Appetite loss that develops suddenly and completely is generally more concerning than a gradual decrease in interest in food.

When a dog presents with loss of appetite, the diagnostic evaluation begins with a thorough history — when the appetite loss started, whether it is partial or complete, and whether any other symptoms are present. A comprehensive physical examination follows, including careful evaluation of the mouth, abdomen, and overall body condition.

Blood work is typically the first diagnostic step, providing information about organ function, blood cell counts, and metabolic parameters that may reveal an underlying illness. A urinalysis may also be recommended to complement the blood work.

Depending on the initial findings, additional diagnostics may include dental radiographs to evaluate tooth roots, X-rays or ultrasoundof the abdomen, and fecal testing for parasites. Your veterinarian will recommend the combination of tests most appropriate for your dog's specific situation.