💛 Vet Guide 2025: Bilious Vomiting Syndrome in Dogs and Cats — Morning Yellow Vomit Explained

Is your dog or cat vomiting yellow foam early in the morning or after a long fast? You’re not alone. This common issue is known as Bilious Vomiting Syndrome (BVS). I’m Dr Duncan Houston, and in this comprehensive 2025 guide, I’ll help you understand the causes, symptoms, and surprisingly simple fixes that can bring your pet relief and help you sleep better too. 🐶🐱

1. What Is Bilious Vomiting Syndrome (BVS)?

Bilious Vomiting Syndrome occurs when bile and stomach acid irritate your pet’s stomach lining after it’s been empty for too long. Bile is a yellow-green digestive fluid made by the liver and stored in the gallbladder. In BVS, your pet vomits small amounts of yellow or white foamy fluid—usually first thing in the morning or late at night. 🌅

This is different from vomiting due to infections, toxins, or organ failure. Pets with BVS are typically otherwise active, happy, and have a good appetite between episodes. That’s one key distinction. 🐾

2. Classic Symptoms of Bilious Vomiting Syndrome

• 🟡 Vomiting yellow, greenish, or foamy fluid
• 🕔 Usually occurs early in the morning or after long fasting periods
• 🐕 Otherwise normal appetite and energy
• 🚫 No accompanying diarrhea or severe lethargy

It’s sometimes referred to as a “hangry stomach” reaction—the stomach gets irritated from being empty too long. Think of it as your pet’s body reminding you it’s time to eat. 😅

3. What Causes BVS?

Bilious vomiting happens because:

• The stomach empties completely several hours after eating
• Bile refluxes from the small intestine back into the stomach
• This bile and gastric acid irritate the stomach lining
• Vomiting clears the irritant—but not the underlying timing problem

It’s most common in pets fed once daily or in the early afternoon, leaving them fasting overnight. ⏳

4. Is It Serious?

BVS is not usually dangerous in otherwise healthy pets—but it must be differentiated from serious causes of vomiting, such as:

• Pancreatitis
• Foreign body ingestion
• Liver or kidney disease
• Food intolerance or inflammatory bowel disease

If your pet shows any of the following, contact your vet:

• 📉 Weight loss
• 🤢 Vomiting more than once daily or after meals
• 😴 Lethargy or weakness
• 🩸 Blood in vomit
• 💧 Changes in thirst or urination

5. Diagnosis

There is no specific test for BVS. Diagnosis is made by:

• 🚫 Ruling out serious illnesses (with bloodwork, X-rays, ultrasound)
• 📋 A consistent history of yellow morning vomit with no other signs
• ✅ Rapid improvement with dietary management

6. Treatment: Simple and Effective!

The great news is BVS usually responds well to changes at home. Here's how: 🥣

6.1 Feed Smaller, More Frequent Meals

• 🍽️ Add a late-night snack (before bedtime)
• 🕔 Feed 2–3 small meals instead of one large meal
• 🥚 Use easy-to-digest food: boiled chicken, rice, or prescription GI diets

6.2 Don’t Increase Daily Calories

Space meals out—but don’t overfeed. The goal is meal timing, not calorie increase.

6.3 Medications (if needed)

• Antacids (famotidine or omeprazole) — reduce acid irritation
• Prokinetics (metoclopramide) — improve gastric motility
• Anti-nausea meds (maropitant) — for ongoing symptoms

Your vet will decide if meds are needed based on frequency and severity.

7. Feeding Tips for Success

• ⏰ Keep meal times consistent
• 🥚 Add protein-rich bedtime snacks like boiled egg or chicken
• 🥄 Keep portions small to avoid weight gain
• 💧 Ensure water is always available

8. Can Cats Get Bilious Vomiting Syndrome?

Yes! Cats can also experience early morning vomiting due to an empty stomach. It’s especially common in:

• Indoor cats fed only once or twice daily
• Cats prone to hairballs
• Cats who eat quickly and vomit afterward

🐱 Add extra small wet meals or overnight feeding toys for feline-friendly fixes.

9. Ask A Vet: When in Doubt, Reach Out

If your pet vomits more than once or shows unusual signs, don’t assume it’s BVS. The Ask A Vet platform offers real-time chat with licensed veterinarians. We’ll help assess symptoms, review test results, and confirm if BVS is likely—or if urgent care is needed. 🩺📲

Download the Ask A Vet app to get answers quickly, day or night. 💬

10. BVS at a Glance

11. Final Thoughts

Bilious Vomiting Syndrome can be unsettling—but it’s manageable. Feeding adjustments and occasional medications often resolve the issue quickly. 🐾

If vomiting continues, worsens, or includes other symptoms, always seek professional advice. A simple change in feeding time can make a world of difference—but don’t let a serious illness go unnoticed. ⏳

— Dr Duncan Houston BVSc

For fast help and personalized feeding advice, visit AskAVet.com or download the app today. 💙🐶🐱