Bilious Vomiting Syndrome (BVS) in Cats

Melissa Boldan, DVM
By Melissa Boldan, DVM on Nov. 27, 2023
A cat is held by their vet.

In This Article


What Is Bilious Vomiting Syndrome in Cats?

Cats can vomit for a variety of reasons. Sometimes the reason is  serious, such as underlying organ dysfunction. Other times, cats may vomit due to more simple problems, like hairballs. And when cats throw up yellow liquid, they may be vomiting bile or stomach acid.

Bile is a substance that is made in the liver and stored in the gallbladder. It is greenish in color and helps with digestion, secreted in the small intestine to break down food.

When bile builds up it can back up into the stomach, which irritates the stomach lining. Cats can vomit up bile or stomach acid when their stomach has been empty for prolonged periods.

Usually, if a cat vomits yellow liquid it is due to some underlying cause, whether a primary gastrointestinal issue or because another system in their body is not functioning properly. Rarely, cats will vomit because of bilious vomiting syndrome (BVS).

BVS is a common condition in dogs, but it is rarely seen in cats. It’s characterized by vomiting up stomach acid or bile, usually overnight or first thing in the morning when a cat’s stomach has been empty for a while.

While BVS is not considered a medical emergency, vomiting can be. Cats with this condition may vomit first thing in the morning, but they act normally otherwise.

These cats eat, drink, and play as usual. This chronic condition can look very similar to persistent vomiting that is seen with many other diseases, so it’s important to talk to your veterinarian.

If your cat is not eating, weak, lethargic, or vomiting several times in an hour (protracted vomiting), seek veterinary care right away.

Symptoms of Bilious Vomiting Syndrome in Cats

Symptoms of BVS in cats include:

  • Vomiting up yellow or green liquid

Causes of Bilious Vomiting Syndrome in Cats

While the exact cause of BVS in cats is unknown, it’s believed to be the result of a motility (pace of food movement) issue with the GI tract.

The duodenum is the first segment of the small intestine. When it’s irritated (sometimes by parasites like Giardia or from chronic inflammatory bowel disease (IBD), it can lead to reflux. IBD is a condition that leads to thickening of a cat’s intestines. The thickened bowel does not have the good motility as a normal bowel, which can result in delayed emptying of the colon and reflux of bile from the small intestine into the stomach. 

Duodenal reflux is the movement of intestinal contents backward into the stomach, rather than forward down the GI tract. When the bile enters the stomach, it causes irritation to the lining. This causes a cat to vomit bile.

BVS is typically seen in cats with concurrent diseases like IBD.

How Veterinarians Diagnose Bilious Vomiting Syndrome in Cats

BVS is usually more of a diagnosis of exclusion, meaning your vet will want to rule out more common illnesses before diagnosing your cat with this condition.

While your vet will start with a physical exam and history, they will likely want to run bloodwork, do a urinalysis, and take X-rays to look for any abnormalities.

For a cat experiencing weight loss or chronic vomiting, a vet may test for feline leukemia, feline immunodeficiency virus (FIV), and thyroid issues. They may also recommend an abdominal ultrasound.

Other causes of chronic, intermittent vomiting that your vet will want to rule out include:

Be sure to tell your vet when the vomiting episodes started and what frequency they are occurring. It’s helpful if you can keep a log of what time of day they vomit and what the vomit looks like. For example, is it always yellow-green, or does it sometimes contain undigested food?

Treatment of Bilious Vomiting Syndrome in Cats

Bilious vomiting syndrome can’t be cured. However, it can typically be managed by feeding a cat smaller meal more frequently.

Pets that have this condition often vomit in the morning after a long fast, having not eaten since an early dinner the previous day. Feeding a snack right before bed can be helpful in stimulating your cat’s GI tract to digest the meal and help propel stomach contents forward. Prescription diets may be recommended by your vet.

BVS may be managed with medications. Acid reducers can help minimize irritation of a cat’s stomach that occurs when bile backs up. Famotidine, an over-the-counter antacid, is often prescribed.

Additionally, some cats may benefit from a pro-motility medication, like metoclopramide or cisapride, to aid in normal digestion.

If your cat developed BVS secondary to another underlying cause, your vet may prescribe additional medications to treat those conditions.

Recovery and Management of Bilious Vomiting Syndrome in Cats

Management of BVS is usually centered around promoting good motility of the stomach and intestines. This motility can be stimulated by feeding small meals more frequently. Feeding small meals three to six times per day can reduce the amount of time your cat has an empty stomach.

Remember, if you are adding in a late-night snack or small meals midday, be sure to reduce the total quantity fed during normal mealtimes.

Make sure that the total amount of food fed is the same; just split up into smaller portions throughout the day. Avoid overfeeding your cat too many calories, as obesity can lead to many issues down the road.

Sometimes prescription diets are recommended in cats that vomit frequently. Your veterinarian may recommend a trial of a highly digestible diet like Hills® i/d Digestive Care, Royal Canin® Gastrointestinal, or Purina® EN Gastroenteric. Some cats may benefit from a hypoallergenic or novel protein diet like Hills® z/d or Royal Canin® Selected Protein.

Occasionally, switching to a canned food diet can be helpful in promoting quicker stomach emptying, as dry food takes longer to move out of the stomach.

Prevention of Bilious Vomiting Syndrome in Cats

While there is no way to prevent BVS, you can reduce your cat’s risk of developing this condition.

Preventing the stomach from being empty for long periods of time by feeding smaller, more frequent meals may reduce your cat’s risk of struggling with bilious vomiting syndrome.

Bilious Vomiting Syndrome in Cats FAQs

How do you know if vomit is bilious?

“Bilious” means that the vomit contains bile. Bile is greenish yellow in color. Vomit that contains bile usually has a greenish or dark yellow color.

Is bilious vomiting syndrome serious?

Bilious vomiting syndrome itself is not very serious. However, if a cat develops aspiration pneumonia secondary to vomiting, that can be serious.

Featured Image: bymuratdeniz/E+ via Getty Images



Cote, E. Bilious Vomiting Syndrome. Clinical Veterinary Advisor, 3rd edition, pp 119–120. (2020)

Mott, J. Bilious Vomiting Syndrome. Blackwell's Five-Minute Veterinary Consult Clinical Companion: Small Animal Gastrointestinal Diseases. (2019)


Melissa Boldan, DVM


Melissa Boldan, DVM


Dr. Melissa Boldan graduated from the University of Missouri College of Veterinary Medicine in 2012. She initially practiced mixed animal...

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