Bilious Vomiting Syndrome in Dogs


  • What Is Bilious Vomiting Syndrome?
  • Symptoms
  • Causes
  • Diagnosing
  • Treatment
  • Prognosis
  • Prevention

For dogs that vomit bile on occasion and are otherwise in good health, with a normal body weight and energy level, bilious vomiting syndrome may be one possible diagnosis your vet considers. This is a condition that occurs regularly in some dogs, with young, male, neutered, mixed-breed dogs being most commonly diagnosed with the condition. Learn more about bilious vomiting syndrome and what you can do to make your dog more comfortable if they are diagnosed with this condition.

What Is Bilious Vomiting Syndrome?

Bilious vomit describes vomit that looks like clear fluid, foam and/or bright yellowish liquid. This liquid is thought to be a combination of fluid from the stomach mixed with bile, a yellow liquid secreted by the gall bladder that aids in digestion. This is different than other kinds of vomiting where a dog may be vomiting up food and/or foreign material.

Bilious vomiting syndrome will typically be a pattern where dogs are vomiting bilious fluid when their stomachs are empty, such as early in the morning or after a long fast between meals. This is almost always a recurring or chronic condition, meaning that it happens frequently.  This might be daily, a few times a week, or a few times a month.  Usually, these dogs only vomit once, or a few times in a row, and then are fine for the rest of the day.

Symptoms of Bilious Vomiting Syndrome in Dogs

The main symptom of bilious vomiting is frequently vomiting this mix of clear, foamy, or yellowish liquid despite being healthy and able to keep food and water down otherwise.  Some dogs that have this condition will also have a lot of gurgling sounds in their belly. They may appear nauseous by licking their lips, drooling, and/or gagging. Sometimes, they will be reluctant to eat their food when it is offered as a result of this nauseous feeling. It is important to discuss these signs with your veterinarian and not assume this condition for your pet as other illnesses like blockages, parasites, or more can look like this.


  • Clear, foamy, or yellow vomit
  • Vomiting on an empty stomach
  • Gurgling belly sounds
  • Licking lips
  • Drooling
  • Gagging
  • Not interested in food when first offered

What Causes Bilious Vomiting Syndrome in Dogs?

Bilious vomiting is thought to have a few contributing factors but in most cases, the exact cause is not determined. It is often known as idiopathic bilious vomiting syndrome, which means the exact cause is not known. Many times, this condition occurs due to the stomach being empty for a long period of time, combined with an over secretion of stomach acid or reflux of fluids from the intestines back into the stomach.

This can lead to feelings of nausea as well as irritation of the stomach. The condition is also known as reflux gastritis for this reason, which simply means irritation of the stomach due to reflux. As a result of stomach irritation and nausea, these dogs vomit but since there is no food in their stomachs, they only vomit foamy liquid.

How Do Vets Diagnose Bilious Vomiting Syndrome in Dogs?

Veterinarians diagnose this condition through a combination of a careful history of the signs and the pattern of the vomiting as well as tests that help to rule out other causes of vomiting. Your vet will want to know what the vomit looks like, how often it happens, what time of day this occurs, and any other symptoms your dog might have.

It is very important to check for other possible causes of vomiting that could be more serious and require specialized treatment. Your vet will likely want to do some diagnostic tests to rule out these other possible causes. This may include blood tests, testing a fecal sample for parasites, X-rays, an ultrasound, and/or endoscopy with biopsies of the stomach and intestines.

How to Treat Bilious Vomiting Syndrome

If your vet determines that your dog does in fact have bilious vomiting syndrome and all the other tests are normal, the treatment is aimed at preventing those factors that lead to vomiting. One important tip is to try feeding smaller, more frequent meals throughout the day, including a late night snack for those dogs that vomit early in the morning. This helps to prevent the stomach from being empty for too long and may reduce the likelihood of vomiting. It is important to remember not to increase the total amount of food your dog is eating each day, but to make each meal smaller to spread out the feedings and avoid weight gain.

In some cases, your vet may also recommend a daily medication to help reduce the acidity of the stomach, protect the lining of the stomach and/or improve motility, which is the movement of fluid and food through the digestive tract. Your vet will choose a medication that is appropriate for your dog given any other health conditions or medications your dog takes.

Prognosis for Dogs with Bilious Vomiting Syndrome

The prognosis for this condition is very favorable in that it does not typically cause serious problems and is more of a nuisance than anything else. Most dogs will respond very well to the treatment plan mentioned above and the condition may completely resolve or at least become much less frequent. For dogs who do not improve or seem to be getting worse, it is very important to follow up with a veterinarian as these dogs have another condition and will need additional tests and treatments.

How to Prevent Bilious Vomiting Syndrome

Fortunately, most dogs will never experience bilious vomiting so nothing needs to be done to try to prevent it in healthy dogs. For dogs that have had this condition at some point, it is a good idea to continue feeding small frequent meals forever. This is a great, safe strategy to prevent the stomach from being empty for too long and may prevent future episodes of bilious vomiting. Other dogs may need to stay on medication long term if the frequent feedings are not enough to control their symptoms.

Some dogs may also benefit from a diet change based on your vet’s recommendations. It is important to consult your veterinarian if you see a sudden change in your dog’s symptoms including more frequent vomiting, a different appearance to the vomit or a change in the pattern and timing of the episodes. Also be sure to report any other new symptoms such as tiredness or diarrhea, as these would suggest a different problem altogether and warrant further examination and testing.

The Spruce Pets uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

  1. Ferguson, Leah, et al. Bilious Vomiting Syndrome in Dogs: Retrospective Study of 20 Cases (2002–2012). Journal of the American Animal Hospital Association, Vol 52, no. 3, 2016, pp. 157-161., doi:10.5326/JAAHA-MS-6300
  2. Linder, Deborah E. Stomaching the Problem: Does your Pet Have Bilious Vomiting Syndrome? Petfoodology. June 17, 2021.
  3. Webb, Craig. Vomiting in Dogs: Chronic (Long-Term) Vomiting. Merck Veterinary Manual. October 2022.
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