How Long Can a Dog Go Without Food according to The Vet

All dog owners are familiar with an old cliche about dogs, “they will eat everything you put in front of them.” Granted, not all dogs have voracious eating habits, but generally, they won’t say not to foods given on their regular feeding schedule. When a dog’s eating habit changes, it is usually a sign of something that is not right.

how long can a dog go without food

How long can a dog go without food? According to book The Complete Book of Questions Dog Owners Ask Their Vet & Answers, under normal circumstances, small dogs can go for about three days without eating, and large dogs can go for about five days without food.

However, each dog can have different conditions. Dogs who are pregnant, sick, underweight, very young, or very old may have different tolerance levels. Therefore, you should not wait longer than 48 hours before trying to determine the cause and the most appropriate solution. Waiting too long can make your dog’s condition worse. 

Keep reading to figure out what are the reasons why your dog doesn’t want to eat and what you can do about it.

Reasons a Dog Won’t Eat

All the reasons as to why a habit as basic as eating can change can be categorized into two main reasons: psychology or physiology. Let’s take a look in more detail.

1. Medical Issues

If you see your dog refusing his kibble, the first thing you should suspect is that there is something wrong with his health. Even though your suspicion turns out to be wrong, it’s better to be safe than sorry.

Here’re some of the most common health problems that may cause your dog to lose his appetite:

  • Stomach issues like upset stomach and bloating
  • Allergies
  • Infection (bacterial, fungal, or viral)
  • Pain
  • Parasites
  • Dental problems
  • Autoimmune disease
  • Cushing’s disease
  • Severe health conditions like cancer, organ failure, diabetes, parvo, pancreatitis
  • Vaccination
  • Conflicting medication
  • Post-surgery

2. Psychological Issues

Like humans, dogs can suffer from mental issues that can be induced by changes in the environment or lifestyle changes. 

Have you moved recently, or has there been a change in your household? For example, did you get married, or have you adopted a new dog? Or have you unconsciously made a change in the way you feed him? Maybe you used to pet him before putting food in his bowl, and now you’re not doing that anymore.

Things like this can lead to stress, anxiety, and depression, which can trigger dogs’ loss of interest in food. Even though these issues are sometimes hard to detect, once you figure out what is causing your pooch to feel depressed, it’s easy to treat.

3. Picky Eaters

Although it’s more common with cats, dogs can be finicky with their foods too. You might be shocked to notice how fast they gobbled up one recipe for a few months and then, all of a sudden didn’t even want to touch it. Meanwhile, there is nothing wrong with their health, according to your vet.

4. Food Issues

Your dog’s food refusal can be caused by food issues; three of the most notable are food allergies, spoiled food, and dietary changes.

Food Allergies

Food allergies occur when a dog’s immune system mistakenly identifies a protein in a certain food as dangerous and harmful. As a result of this misidentification, your dog may experience a number of symptoms, including loss of appetite, vomiting, and diarrhea, among other things.

Spoiled Food

Once in a while, you buy dog food online and unluckily have a spoiled or contaminated product delivered. This could happen to anyone; I have experienced it two times so far. Fortunately, spoiled food is easy to point out as the signs are quite obvious.

You can tell if your dog food has gone off if:

  • You can smell a sour or rancid odor.
  • You can see visible molds, bugs, or fungi.
  • You can see that the food is discolored.
  • You can see from the bag that the food is past its expiration date.
  • You can find signs of exposure to heat or humidity.

If you notice any of those signs, there is a high chance that the food has gone rancid and should be thrown away.

Diet Changes

As your dog gets older, you will need to change his diet as well to accommodate his nutritional needs. A sudden switch in foods can cause digestive issues that make your dog want to skin his meals.

What Should You Do if Your Dog Won’t Eat?

Here are some steps that you can try right away when the dog suddenly stops taking his food:

  • First of all, stay calm and don’t freak out. Once in a while, it’s normal for dogs to fast for a day or two. I don’t know what the reason is, but my dog does this too. This is fine as long as they don’t show any signs of illness or depression.
  • While you’re waiting for a maximum of 48 hours, try to find out the reason why your pooch won’t eat. Check out the list of possible reasons that I’d written above.
  • Try to boost his appetite by offering his favorite treats. If he quickly grabs them up, then the problem can be traced to a food issue. 
  • If your dog is still refusing to eat after 48 hours, then you should seek help from your vet immediately. 

How to Treat Loss of Appetite in Dogs Caused by Food

Some health issues are treatable by yourself, while others will require professional support. Food-related loss of appetite is one of those issues that, in many cases, you can treat yourself. 

Food Allergies

To treat food allergies in dogs, you need to find the ingredients that cause an allergic reaction. It’s best to bring your dog to the vet. He or she will then run a test to rule out the ingredients that your dog is sensitive to.

Generally speaking, dogs’ food allergies are triggered by either common proteins (like chicken, beef, and lamb) or grains. Depending on the allergen, the solution to this problem is as simple as changing your dog’s food—novel protein dog food, grain-free dog food, or homemade diet.

Food Changes

Whatever the reason is, whether you need to change your dog’s diet because of his allergy or because he’s aging, food changes should be done gradually to avoid digestive upset or tummy trouble.


I know this is cumbersome, but nothing you can do about a dog’s finicky eating other than keeps trying to find that one recipe that will make him drool the most.

How to Treat Loss of Appetite in Dogs Caused by Physiological Issue

Before you can treat your dog’s mental conditions, you need to make sure that the cause of your dog’s sudden loss of appetite is indeed mental issues and then work to identify the root cause of the behavior and fix it. Most often, it’s not that easy to do it as the signs can be too subtle to notice, so it’s better to work together with a vet, too, in this case.

New Puppy Won’t Eat

A new puppy may be reluctant to eat in a new environment away from his littermates and mother. Just be patient and give him time to adjust to his new home. Here’re a few things that you may want to do to help him feel welcome:

  • Take him on a stroll around the house and neighborhood.
  • Play with him often.
  • Introduce him to all members of the families, both human and animal.

Related Questions

1. How long can sick dogs go without food?

Sick dogs should not go beyond 24 hours without food or water. This is more prevalent, especially if your dog has also been vomiting and having diarrhea. If, after 24 hours, your dog still hasn’t had even a sip of water, take him to the vet ASAP.

2. How do I feed my sick dog with no appetite?

Some of the most popular foods to feed your dog he’s sick are chicken and rice, shredded chicken, pumpkin, bone broth, and baby food. Make sure to check with your vet before feeding any of these foods.

3. Why is my dog not eating but drinking a lot of water?

This could be a sign of a health problem such as Diabetes Insipidus. This rare disorder prevents the dog’s body from conserving water and releasing too much of it, which may lead to excessive thirst.