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Is your dog regularly throwing up yellow foam or fluid, but it’s limited to the early morning hours? If they appear otherwise healthy, they could be suffering from bilious vomiting syndrome, also known as reflux gastritis or duodenal gastric reflux.

Fortunately, bilious vomiting syndrome (BVS) in dogs is usually easy to treat. However, vomiting yellow liquid can be a sign of more serious conditions, so learning when it’s a cause for concern and when you should see a vet is helpful.

What Causes Bilious Vomiting Syndrome in Dogs?

Dr. Sara Jablonski is an Assistant Professor in Small Animal Clinical Sciences at the College of Veterinary Medicine, Michigan State University. She explains that BVS is a clinical condition and the exact cause isn’t fully understood.

However, Dr. Jablonski says experts believe this type of vomiting in dogs relates to altered gastric motility and bile-induced stomach inflammation (gastritis). “What is potentially happening is that, at certain times, pressure in the stomach (called intragastric pressure) isn’t high enough to prevent the backflow of material from the duodenum [the first part of the small intestine] into the stomach,” she says. “The bile that comes from the small intestine is damaging to the stomach when it’s empty.” This temporary inflammation and irritation to the stomach lining triggers the vomiting reflex.

Samoyed laying outdoors, mouth wide open.
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Bilious vomiting syndrome usually occurs in the early hours of the morning. Dr. Craig Webb, Professor in the Clinical Sciences Department at Colorado State University Veterinary Teaching Hospital, explains this is because it involves the motility pattern that occurs during a long period of fasting. Because the dog hasn’t eaten for hours, the vomit is typically a foodless yellow froth or fluid.

You can see bilious vomiting syndrome in dogs of any age, size or breed. “It seems to occur most often in young, adult, mid-sized, otherwise healthy dogs, and there is no particular breed disposition,” Dr. Webb says.

What Are Signs of Bilious Vomiting Syndrome in Dogs?

Dr. Jablonski says the classic sign of BVS is intermittent early morning vomiting of yellow-tinged fluid in dogs that appear otherwise healthy. “They will have good appetites, normal energy levels, and no history of weight loss or diarrhea,” she says. “The dog may sometimes exhibit other signs associated with nausea, like lip-smacking or drooling.” They might also be panting because of the discomfort and have a temporary decrease in appetite. Dr. Webb explains the dog will usually feel fine after vomiting and resetting to daytime motility.

When Should You Take a Dog Vomiting Bile to the Vet?

Often, bilious vomiting syndrome in dogs is easy to resolve with at-home treatment. “The best first attempt at treatment is to feed the dog a portion of dinner as a ‘late-night snack,’ hopefully reducing the length of the overnight fast,” Dr. Webb says. However, Dr. Jablonski stresses it’s only appropriate to try this if your dog appears otherwise healthy. “If they are also experiencing things like diarrhea, vomiting at other times of the day, or a prolonged decrease or change in appetite, this can be a red flag that there’s something else going on,” she says.

Bulldog puppy getting a check-up at the vet.
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Don’t delay making an appointment if your dog displays other symptoms on top of the early morning vomiting of yellow bile. Although bilious vomiting syndrome isn’t typically life-threatening, things like intestinal obstructions can become veterinary emergencies when there is a delay in treatment.

Some concerning signs to look out for include:

  • Diarrhea

  • Severe or persistent vomiting, especially if they’re unable to keep food or water down

  • Retching without bringing up any food or fluid

  • Retching and producing only thick saliva
  • Weight loss

  • Breathing fast or shallowly

  • Pacing, hunching or whining in discomfort

  • Lethargy

  • Abdominal bloating or distension

  • Collapse

You should also seek further support from your veterinarian if the late-night meal doesn’t resolve the BVS, even if your dog appears otherwise healthy.

How Do You Diagnose Bilious Vomiting Syndrome in Dogs?

“Bilious vomiting syndrome is typically suspected in dogs that are feeling well and simply displaying intermittent vomiting of yellow bilious fluid, most commonly in the early morning,” Dr. Jablonski says.

If the dog displays other symptoms, she explains that throwing up yellow vomit could be a component of another problem. Your veterinarian will want to evaluate your dog and run additional diagnostic tests. “These could include blood tests and imaging of the abdomen (maybe x-rays or an ultrasound),” Dr. Jablonski says. “In this sort of scenario, BVS would be a clinical diagnosis of exclusion, as you have to make sure that it’s not something more serious that requires a different treatment approach.”

What Else Can Cause Dogs to Throw Up Yellow Foam?

Beagle laying down next to a full bowl of kibble.
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“Vomiting can occur for a whole host of reasons in dogs,” Dr. Jablonski says. Sometimes, vomiting clears up without veterinary assistance. Other times, it isn’t serious but requires treatment, and there are occasions when it can relate to a life-threatening issue. This is why paying attention to when your dog is throwing up yellow fluid and if they’re experiencing any other symptoms is important.

Dr. Jablonski says intestinal blockages and acute pancreatitis are two of the most common reasons why dogs would throw up yellow foam. However, with these and most other causes, your dog will do more than vomit. “With an intestinal blockage, for example, initially, your dog could just be vomiting in the early morning and feeling okay,” she says. “But after a short period of time, they will probably not be eating and not acting well at all.”

Some other reasons your dog could be throwing up yellow vomit include:

What Are Treatment Options for Bilious Vomiting Syndrome in Dogs?

Fortunately, introducing a late-night meal is often enough to increase gastric motility, buffer the bile in the stomach, and solve the problem. However, if your dog has a bilious vomiting syndrome diagnosis but continues to throw up yellow fluid, even with a feeding schedule change, there are other treatment options.

Dr. Webb explains that sometimes, there is an assumption that acid-reducing drugs might help. However, he says these won’t have any effect because this is a gastrointestinal motility issue, not an “acid-stomach” one. He says anti-vomit medications won’t work either. Instead, promotility drugs or other dietary changes are often successful in managing the symptoms of BVS.

“Sometimes switching to a veterinary gastrointestinal prescription diet can be beneficial,” Dr. Jablonski says. Another option is to administer a single dose of promotility drug at bedtime. Cisapride is a common prokinetic, but your veterinarian can talk you through the options. “These drugs may be beneficial, however, because this is not a very well-defined syndrome with lots of studies, their success is based on anecdotal evidence,” Dr. Jablonski says.

This article is intended solely as general guidance, and does not constitute health or other professional advice. Individual situations and applicable laws vary by jurisdiction, and you are encouraged to obtain appropriate advice from qualified professionals in the applicable jurisdictions. We make no representations or warranties concerning any course of action taken by any person following or otherwise using the information offered or provided in this article, including any such information associated with and provided in connection with third-party products, and we will not be liable for any direct, indirect, consequential, special, exemplary or other damages that may result, including but not limited to economic loss, injury, illness or death.
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