French Bulldog Vomiting Foam. Your dog is most likely throwing up white liquid because theres not much else in his stomach to purge. What this means is that foam is more likely to be in their vomit if they have an empty stomach.

Vomiting white foam due to tracheal collapse. Why is my French Bulldog throwing up white foam When your Frenchies vomit has white foam in it thats usually caused by the vomit reacting with the air around it. The food rich in fibers presents one of the most common reasons for a Frenchies watery stools.
Vomiting is usually seen in the morning or late night just before eating especially in dogs that are fed once daily.
Food rich in chicken skin eggs and dairy products should also be avoided. In certain situations liquid vomiting that is yellow or clear is a symptom of an entirely different medical problem. They often show an allergy to oily food rich in by-products. What this means is that foam is more likely to be in their vomit if they have an empty stomach.