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Bilious vomiting syndrome

As the name sounds, bilious vomiting syndrome (BVS) stems from the bile in a dog’s stomach. Bile is a yellowish-green bitter substance — made of water, bile acids, cholesterol, fatty acids, and electrolytes — that aids in the digestion process by breaking down fats.

When a dog’s stomach is empty, there’s nothing to absorb the stomach acids and bile. The excess bile can lead to stomach irritation and sometimes cause nausea and vomiting up bilious liquid, hence the name. The condition can be tricky to treat because nausea and vomiting cause a dog to not want to eat, which leads to an even more empty stomach — and more nausea and vomiting. It can become a difficult ongoing cycle.

What causes bilious vomiting in dogs

Accumulated bile in the small intestine can leak into the stomach, which is irritating to the stomach lining due to the high acidity of bile. Because an empty stomach can’t absorb the bile, a dog will typically become nauseated and start vomiting the bilious liquid.

👉 Bilious vomiting can happen to any dog with no known underlying cause.

It’s important to remember that, even though BVS occurs in the digestive system, it shouldn’t be confused with inflammatory bowel disease or gastroenteritis — these may have bilious vomit as a symptom, but are typically caused by something other than bile entering an empty stomach.


The most common symptoms of BVS are: 

  • Frothy yellow vomit
  • Vomiting occurring in the morning or at night
  • A lack of appetite

👉 Aside from these symptoms, dogs with BVS usually act completely normal otherwise.

How it’s diagnosed

In order for your veterinarian to determine a diagnosis, they’ll want to go over your pup’s medical history and will likely ask you questions about your concerns. These questions could include what time the vomiting usually occurs, if it’s been ongoing, what kind of diet your dog is currently on, or how often they’re fed. 

BVS is a diagnosis of exclusion — in other words, because bile vomiting can be caused by a variety of conditions (i.e. gastritis, giardiasis, bowel obstruction, etc.), the primary goal of the vet appointment is to rule out all other potential causes of the vomiting. Once everything else is ruled out, they can come to the conclusion that it’s, in fact, BVS. They’ll want to do a hands-on exam and may suggest other tests including a blood panel, abdominal x-rays, a fecal exam, or urinalysis, etc. in order to determine all of this and come up with the best treatment plan.

How BVS is treated

There are a few ways to start treating a dog with bilious vomiting syndrome:

Take medications from the vet — Your dog may be prescribed H2 blockers, like famotidine (i.e. Pepcid), to help reduce the amount of stomach acid being produced. Sucralfate may also be recommended for a short period of time to help coat and protect your pup’s stomach and esophagus from irritation.

Give snacks before bed — More frequently fed small meals will keep your dog’s stomach full and can help prevent acid from irritating the stomach lining. Giving them a snack just before bed may keep them from vomiting in the morning. 

Hydrate after vomiting — If your dog is suffering from dehydration from chronic vomiting, your vet may start an IV to replace lost fluids. 

👉 This is typically seen if the bilious vomiting is coming from an underlying cause and rarely from BVS alone.

Should you consider changing your pup’s diet?

If your dog is vomiting bile on a regular basis, changing their diet might help prevent bilious vomit syndrome from happening. This could look like more frequent feedings, changing the time of feeding, or changing your dog’s food. 

If your dog’s food isn’t causing an issue, you can try feeding your pup right before going to bed — or just giving them a small bedtime snack — and again first thing in the morning. This helps prevent your pup from having an empty stomach for too long overnight. If your veterinarian is suspicious of food allergies, they may recommend changing the diet to a prescription diet or a diet formulated for sensitive stomachs. These foods are typically more digestible, have fewer ingredients, or have an overall more “bland” composition to be easier on their GI tract. 

Owners can also help their dog’s upset stomach by feeding a plain chicken and rice mix for a few meals to give their digestive tract time to settle. 

👉 It’s important to note, however, that this is not a well-balanced meal and shouldn’t be used long term.