Quick answer: Morning vomiting is often caused by bilious vomiting syndrome — bile accumulates in an empty stomach overnight and causes nausea.
When a dog goes too long without food, bile from the digestive system irritates the stomach lining, causing yellow or foamy vomit — usually in the early morning before breakfast. It looks alarming but is one of the most common and easily solved dog issues: a small snack before bed usually fixes it within days.
Eating grass the day before, eating too fast, motion sensitivity, or a diet change can also lead to morning vomiting. Check what the vomit looks like: yellow or foamy points to bile; food chunks suggest the issue is digestion-related.
If morning vomiting continues daily for more than a week despite dietary adjustments, or if it's accompanied by blood, lethargy, weight loss, or appetite changes, see a vet. Chronic vomiting can indicate gastritis, parasites, food intolerance, or other conditions.
A late-night kibble snack fixes most cases of morning bile vomiting. If that doesn't help within a week, a vet visit is the right next step.