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Why Is My Dog Throwing Up Undigested Food? When to Be Concerned

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Updated May 26, 2023


If you have a dog, there’s a good chance that you’ll see them throw up at some point or another. Dogs vomit occasionally — it’s just one of those things that is a part of life when you share your home with a canine companion.

But while one isolated episode of vomiting might not be a huge cause for concern, that doesn’t mean vomiting is nothing to worry about. What happens if your dog is vomiting frequently or if they’re throwing up undigested food?

There are many, many reasons why a dog might vomit. And to make matters more confusing, vomiting is technically not the same thing as regurgitation, even though we tend to think of the terms as having the same definition. So what exactly causes vomiting in dogs, and what can you do about it?

Let’s take a closer look at this unpleasant aspect of dog ownership and care. That way, you’ll know when to be concerned and what to do next.


Your Dog's Digestive System

Before we jump into the why dogs might throw up, it’s important to understand how a their digestive system works and what can go wrong.

When your pup eats something, their stomach breaks down the food using hydrochloric acid and enzymes. The partially digested contents enter their small intestine where nutrients are absorbed before the waste is passed into the large intestine. Your dog's digestive tract is designed to absorb the nutrients and then expel the rest.

When your pup isn’t feeling well, they may vomit up their partially digested food. But if your pup is throwing up undigested food — meaning it appears almost exactly as when they ate it — that could be a sign of an underlying condition like an obstruction or a bacterial infection.

In any case, if your pup is vomiting up their food more than two or three times in one day, it’s time to call the vet. The same is true if they’re having trouble keeping anything down — even water! Your pup might also experience lethargy and loss of appetite when their digestion is off.

It’s always a good idea to take your pup in for an exam if they’re experiencing vomiting, regardless of the frequency or contents. That way, you can get to the root cause and treat it before it gets worse.

Difference Between Vomiting vs. Regurgitation

Most of the time, we think of vomiting and regurgitation as the same thing. But these terms refer to different actions in dogs.

Regurgitation is the return of food into the oral cavity after it has been swallowed. The food never started getting digested before it was expelled — your pup’s abdominal muscles didn’t push the stomach contents back up into the esophagus and mouth. A combination of the esophageal muscles and gravity did.

Vomiting, on the other hand, does involve the muscles in the abdomen pushing stomach contents out of the stomach and back into the esophagus and mouth. Those contents will be partially digested. Vomiting is more of an active experience for your dog while regurgitation can happen passively without your pooch really controlling it.

Why does regurgitation occur? Typically, it happens when your dog:

  • Eats too much
  • Eats too fast
  • Experiences stress, anxiety, or over-excitement
  • Suffers from a dilated esophagus (megaesophagus), a condition that causes the esophagus to expand and fail to move food into the stomach correctly

So, regurgitation is something that many dogs can experience without actually having something medically wrong with them. (The exception is megaesophagus, and you should contact your veterinarian if your dog regurgitates frequently.) Vomiting, though, is more concerning.

look up cute puppy

Causes of Vomiting

Before your dog vomits, you’ll probably see them pace around for a few moments, then they’ll begin gagging and retching before vomiting. Along with partially digested dog food, the stomach contents will probably include some fluid.

If that fluid is clear, then it’s normal stomach fluid. However, if it’s green or yellow, it’s bile and probably came from the small intestine. This means that your dog’s food had already started being digested before your dog threw it up.

The presence of bile isn’t necessarily a cause for concern, but it does mean that your dog’s system is vomiting up stomach contents that had already started getting digested, which is never entirely normal.

So what causes dog vomiting, exactly? There are a multitude of possibilities, including:

  • Viruses
  • Intestinal parasites like hookworms, whipworms, roundworms, or tapeworms
  • Food allergies
  • Ingestion of garbage
  • Ingestion of too much rich, fatty, or buttery food
  • Ingestion of foreign objects (dirt, rocks, clothing, tennis balls, etc.)
  • Liver or kidney health
  • Ingestion of a toxic agent (pesticides, cleaning products, antifreeze, etc.)
  • Motion sickness, most likely when riding in a car

On the contrary, if your dog's starts vomiting blood or shows signs of pain, don’t wait for the vet. Seek emergency care right away — these are possible indications of a serious medical emergency.

No matter the cause of your pup’s vomiting, it’s important to keep a close eye on them and contact your veterinarian if they don’t seem to be improving or if the vomit contains blood. Your vet can provide food suggestions, medications, and other treatments that will get your pup back on the road.


Warning Signs for Dog Parents

The occasional episode of vomiting probably isn’t something to worry about, but you should keep a close eye on your pet after he or she has vomited. If other signs and symptoms accompany the vomiting, it’s time to call the vet.

Watch for:

  • Frequent vomiting. If your pup won’t stop vomiting, it’s a cause for concern. Consult with a vet if you see signs of serious problems.
  • Additional symptoms. Keep an eye on your dog after the vomiting episode. If you notice things like diarrhea, drooling, nasal discharge, sneezing, seizures, or other medical abnormalities, something is wrong. And if your dog’s vomit appears to be bloody — dried blood often looks like coffee grounds in the vomit — they’ll definitely need veterinary attention.
  • Changes in behavior. Have you noticed behavioral changes in your dog after their vomiting? Loss of appetite, weakness, noticeable weight loss, and sensitivity to touch around the abdomen (indicative of abdominal pain) are just a few examples. Let your vet know if you’re concerned about behavioral changes.

You should also be aware of a dangerous condition called bloat, especially if you have a bigger dog — the problem is more common in large breeds. In a case of bloat, a dog’s stomach twists, blocking the escape of stomach contents and forcing the stomach to expand.

One of the telltale signs of bloat is retching and gagging without producing any material. If you see your dog doing this, let your vet know immediately.


Responding to Your Dog’s Vomiting

If your dog is exhibiting frequent vomiting, or if you know or suspect that they’ve ingested something they shouldn’t have like a foreign body or a toxic agent, call your vet right away.

Veterinary care may include a thorough physical exam, x-ray or ultrasound scans, stool sampling, blood tests, and more. A dog who is suffering from chronic vomiting will become dehydrated, and may need IV fluids to correct it.

Once the dog is stable, your veterinarian will go about treating the underlying cause of your dog’s vomiting.

Often, though, you’ll just see your dog vomit once, or regurgitate food they’ve just eaten. In these cases, you’ll want to keep an eye on your pup to see if they exhibit any other symptoms or unusual behaviors. If they don’t, your dog is most likely fine.

Veterinarians also sometimes recommend withholding food and water for a half or full day after a vomiting episode, as this gives the digestive system time to rest and the stomach lining a chance to repair itself.

Then you can try feeding Fido a bland diet of plain white rice and fully cooked chicken for a couple meals until returning them to their normal food. Remember not to feed this long term, as it does not constitute a balanced diet.

You might also try giving your dog a digestive supplement or a probiotic to help his or her digestive system function better as time goes on.



So, What caused it?

At the end of the day, there are many possible reasons why your dog might throw up partially digested or undigested food. They might also regurgitate food that hasn’t even had a chance to be digested.

One of the most common causes is gastritis or simple stomach irritation — usually caused by your dog eating something they shouldn’t — but other serious issues could be to blame.

If your dog vomits once, keep a close eye on them to see if anything else happens. If nothing else occurs, your pup is most likely fine. But if you see additional symptoms or unusual behavior, let your veterinarian know.

You know your dog best. If you think their vomiting warrants concern, play it safe and call your veterinarian. It’s always better to be safe than sorry!