A dog that skips a meal but is otherwise bright and normal is often fine, but a dog that stops eating can also be ill.1,2 Loss of appetite has many causes, from stress, heat or a change of food to nausea, dental pain, infections, pancreatitis, kidney disease and cancer.2,3,4 Puppies, toy breeds and dogs with diabetes can't safely go long without food.5,3 Most adult dogs that haven't eaten for 24 hours, or that skip more than one meal, should see a vet, sooner if there are other signs.1,3,6 This guide explains the common causes, when to worry, what vets check, and how to tempt a dog to eat safely.
Call your vet now, or go to an emergency vet, if your dog isn't eating and:
- Is vomiting, has diarrhea, or is lethargic or weak3,1
- Has a swollen or tight belly, or cries when the belly is touched3
- Is drinking much more than usual3,7
- Is a puppy, especially a toy-breed puppy that is trembling or weak5,8,9
- Has diabetes (ask your vet before giving insulin to a dog that hasn't eaten)1,10
- May have eaten something toxic or swallowed a toy or other object2
What the Research and Guidelines Say
- Puppies can't wait. Puppies, especially toy breeds, shouldn't go more than about 12 hours without food because their blood sugar can drop.5,8
- Hospital feeding support starts within days. Veterinary nutrition guidelines recommend feeding support for hospitalized dogs that haven't eaten for about 2 days, or that have eaten too little for 3. These are treatment thresholds, not safe waiting times at home.11
- Dogs burn muscle when they don't eat. Without food, the body breaks down working muscle and organ protein, which can weaken immunity and slow healing.12,11
- Treats can crowd out meals. Treats should make up no more than 10% of daily calories.3
Why Dogs Stop Eating
Illness
Illness is the most common cause of a sudden loss of appetite.1 Causes include:2,3,4,13,14
- Stomach and intestinal upset, nausea or a blockage from a swallowed object
- Pancreatitis, sometimes after eating garbage or table scraps. See pancreatitis in dogs.
- Kidney disease, liver disease, Addison's disease and diabetes. See kidney disease in dogs.
- Infections, fever and cancer
- Side effects of medicines, such as some antibiotics and pain relievers1,2
Pain
Some dogs want to eat but can't, because of mouth pain, a bad tooth, a mouth tumor, jaw pain or neck and back pain that makes reaching the bowl uncomfortable.2,1
Stress and changes
Moving house, a new pet or baby, visitors, building work or even a moved food bowl can put a dog off food for a while.3,2
Food problems
Stale or spoiled food, a sudden diet change, too many treats or table scraps, and hot weather can all reduce appetite.3,1,2
After vaccines or surgery
A mildly reduced appetite for a day or two after vaccines can be normal. Get care right away for repeated vomiting or diarrhea, hives, facial swelling, trouble breathing or collapse.15 After surgery, many dogs skip a meal the first evening; call your vet if your dog still isn't eating 12 to 24 hours later, or is vomiting.16,17
Won't Eat Food but Will Eat Treats?
Some dogs hold out for something tastier, especially if they get lots of treats or table food. But a dog that used to eat well and suddenly only accepts treats or food with toppers may be feeling unwell, so mention it to your vet.3 Keep treats to no more than 10% of daily calories.3
Not Eating but Drinking Water?
A dog that is drinking normally may simply be off food for a day. But not eating while drinking much more than usual can be a sign of diabetes, kidney disease or another serious illness, and needs a vet promptly.3,7
How Long Can a Dog Go Without Eating?
- Puppies: call your vet if a puppy skips more than one meal; puppies, especially toy breeds, shouldn't go more than about 12 hours without food.1,5
- Healthy adult dogs: call your vet if your dog hasn't eaten within about 24 hours, or sooner if there are any other signs.1,3,6
- Dogs with diabetes or other illnesses: call the same day.1,3
Don't wait several days to see if your dog starts eating again. Changes in appetite can be the first sign of a serious problem.2
What Your Vet Will Do
Your vet will ask about your dog's diet, habits and other signs, check the mouth and teeth, and examine your dog. Tests may include blood tests, X-rays or an ultrasound.2,18 Treatment depends on the cause and may include fluids, anti-nausea medicine, appetite stimulants and, in severe cases, a temporary feeding tube.2,3,11
How to Encourage Your Dog to Eat
If your dog seems otherwise well, or your vet has said it's safe to try:
- Warm the food to about body temperature, around 100°F, to make it smell more appealing. Stir microwaved food to remove hot spots.2
- Add a little warm water or plain low-sodium broth (check it has no onion or garlic), or hand-feed small amounts.3,1
- Check the food is fresh, and feed in a quiet place away from other pets.1,3
- Change foods gradually rather than suddenly.3
- Use a plain, bland diet only for a short time and with your vet's agreement.3,2
- Never force-feed your dog; food can go down the wrong way.11
Older Dogs That Won't Eat
Older dogs need fewer calories, so eating slightly less can be normal, but age alone doesn't explain a dog that stops eating. Dental disease, kidney or liver disease, heart disease, cancer, arthritis and cognitive decline are common reasons in seniors.3,19,18 Softer food, a raised bowl and a non-slip mat can help.3
Frequently Asked Questions
Why is my dog not eating?
Common reasons include illness, nausea, pain, stress and changes to food or routine. If it lasts more than a day or comes with other signs, see your vet.
When should I worry about my dog not eating?
If an adult dog hasn't eaten for about 24 hours, a puppy skips more than one meal, or there's vomiting, lethargy or other signs.
Why is my dog not eating his food but will eat treats?
He may be holding out for tastier food, but a sudden change in a good eater can mean he feels unwell.
What can I give my dog with no appetite?
Try warming the food or adding a little low-sodium broth. Ask your vet before giving any medicine or changing the diet.
Is it normal for a dog not to eat after vaccines?
A slightly reduced appetite for a day or two can be normal. Call your vet if it lasts longer or other signs appear.
My dog is not eating but acting normal. Should I worry?
A single skipped meal is usually fine, but call your vet if it lasts more than about a day.
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Sources and further reading
This article was rewritten and fact-checked on October 18, 2026 against current veterinary references and specialist guidelines:
- Traverse T. Why Won't My Dog Eat? American Kennel Club, updated September 2026.
- Hunter T, Llera R, Downing R. Anorexia in Dogs. VCA Animal Hospitals, updated September 2023.
- Koehler R. Dog Not Eating? Causes and When To Call Your Vet. PetMD (reviewed by Boldan M), updated August 2026.
- Steiner JM. Pancreatitis and Other Disorders of the Pancreas in Dogs. Merck Veterinary Manual (pet owner version), reviewed May 2018, updated December 2024.
- Turner B. Why Your Puppy Isn't Eating & What You Can Do. Preventive Vet, updated November 2025.
- American Animal Hospital Association. What's wrong? Common pet pain signs. AAHA, September 2024.
- Barnes C, Llera R, Weir M, Ward E. Chronic Kidney Disease in Dogs. VCA Animal Hospitals, updated May 2026.
- Purina Pro Club Expert Team. Hypoglycemia in Toy Breeds. Purina Pro Club, April 2018.
- Barnes C, Williams K, Ruotsalo K, Tant MS. Testing for Low Blood Sugar. VCA Animal Hospitals, updated February 2024.
- Merck Animal Health. Handling a Diabetes Emergency. Merck Animal Health USA, accessed October 2026.
- Canadian Academy of Veterinary Nutrition, Abood SK, Llera R, Downing R. Critical Care Nutrition for Dogs. VCA Canada, updated April 2024.
- Delaney SJ, Fascetti AJ, Elliott DA. Indications for Nutritional Support. In: Encyclopedia of Canine Clinical Nutrition. IVIS, 2008.
- Brown SA. Noninfectious Diseases of the Urinary System in Dogs. Merck Veterinary Manual (pet owner version), reviewed June 2018, updated May 2026.
- Van Vertloo L. Addison Disease (Hypoadrenocorticism) in Animals. Merck Veterinary Manual (professional version), reviewed July 2024.
- Tufts Your Dog. What to Watch For After Your Dog's Vaccinations. Your Dog (Cummings School of Veterinary Medicine at Tufts University), accessed October 2026.
- American College of Veterinary Surgeons. Postoperative Care After Surgery: What Animal Owners Should Expect. ACVS, accessed October 2026.
- Fernandez C. Dog Surgery Aftercare: What's Normal and What's Not. PetMD, April 2026.
- Cummings School of Veterinary Medicine at Tufts University. Reduced or Altered Appetite (HeartSmart). Tufts University, accessed October 2026.
- Lap of Love Veterinary Hospice. Why Has My Senior Pet's Appetite Changed? Lap of Love, accessed October 2026.
About this article
Last updated : page rewritten using VCA, Merck Veterinary Manual, PetMD, AKC and veterinary nutrition guidance.
This page is for general information and is not a substitute for an exam by your veterinarian.
