TL;DR: Grass vomiting is typically a low-urgency behavior used by dogs to settle their stomachs or add fiber to their diet. Monitor your dog for additional symptoms like lethargy or persistent vomiting, which may indicate a more serious medical issue.
What causes my dog to eat grass and then vomit?
It is very common for dogs to ingest grass, a behavior sometimes referred to as pica. While the exact reason isn't always clear, many experts believe dogs eat grass to supplement their diet with fiber, or instinctively to induce vomiting when they feel a mild stomach upset. The blades of grass can tickle the throat and stomach lining, triggering the vomit reflex to help expel whatever was causing discomfort.
Is it an emergency if my dog is vomiting grass?
The urgency level for a dog vomiting grass is generally low if your pet continues to act normally, eat well, and stay hydrated. However, you should contact your veterinarian if you observe the following:
- The vomiting becomes frequent or persistent
- Your dog appears lethargic or weak
- There is a noticeable loss of appetite
- Your dog develops diarrhea
Why should I take a photo of my dog's vomit for the veterinarian?
A clear photo of the vomit allows veterinary professionals to triage the situation more accurately. A visual record helps identify:
- The color and consistency of the bile
- The amount of grass ingested
- Signs of blood or parasites
- The presence of foreign objects
Clinical Context (Merck Veterinary Manual)
Dogs often vomit, frequently after eating grass, which may then be present in the vomitus. Causes of vomiting include dietary indiscretion such as ingestion of novel, spoiled, or contaminated foods, or foreign material. Drug or toxin ingestion (e.g., antibiotics, NSAIDs, corticosteroids, plants, chemicals), systemic illness (e.g., pancreatitis, hypoadrenocorticism), endoparasitism, or bacterial or viral infections can also induce vomiting. A specific diagnosis should be sought if the animal has had access to foreign objects or toxins, if clinical signs do not resolve within 2 days of symptomatic therapy, if hematemesis or melena are present, if the animal is systemically unwell, or if abnormalities are noted on abdominal palpation.
Chapter: Pharmacology
Source: The Merck Veterinary Manual, 11th Edition (Page 2547)