TL;DR: Dogs typically vomit yellow bile and eat grass when their stomach is empty or they feel nauseous, but you should consult a veterinarian if it happens more than twice in 24 hours or is accompanied by lethargy.
Why is my dog vomiting yellow bile and eating grass?
Vomiting yellow bile, also known as bilious vomiting, typically occurs when a dog's stomach is empty. The yellow fluid is bile, a digestive enzyme produced by the liver and stored in the gallbladder. Dogs often instinctively eat grass when they feel nauseous or have an upset stomach, as the long strands can wrap around irritants or help induce vomiting to clear their system.
When should I be concerned that my dog's vomiting is an emergency?
- Urgency Level: Medium. While a single episode may just indicate an empty stomach, it should not be ignored if it becomes a pattern.
- Contact a veterinarian if the vomiting occurs more than twice in 24 hours.
- Seek medical attention if your dog is lethargic or shows a complete loss of appetite.
- Monitor for signs of GI inflammation or potential obstruction.
How does taking a photo of the vomit help the veterinarian with triage?
A photo of the vomit and grass can provide vital diagnostic clues, allowing the medical team to evaluate:
- The exact shade and color of the bile.
- The consistency of the fluid.
- The presence of traces of blood or mucus.
- Any visible foreign objects.
- The severity of the irritation to determine the best course of diagnostic testing.
Clinical Context (Merck Veterinary Manual)
In dogs presenting with vomiting, especially after eating grass, the vomitus may contain bile, food, froth, blood (frank or digested), or evidence of the ingested substance. Causes can include dietary indiscretion or intolerance (ingestion of novel, spoiled, or contaminated foods, or of foreign material), drug or toxin ingestion (e.g., antibiotics, NSAIDs, corticosteroids, plants, chemicals), systemic illness (e.g., pancreatitis, hypoadrenocorticism), endoparasitism (e.g., Physaloptera sp), or bacterial (e.g., Helicobacter-associated disease) or viral infections. Diagnosis is usually based on a thorough history, clinical findings, and response to symptomatic treatment.
Chapter: Gastroenterology, Hepatology
Source: The Merck Veterinary Manual, 11th Edition (Page 479)