Dogs vomiting yellow water, foamy mucus may be because they are too hungry. The yellow water is actually the dog’s gastric juice, or it may be the dog’s indigestion, which is the phenomenon of regurgitation and vomiting in dogs.

This will also happen if the dog eats food that it cannot digest. , these indigestible foods may cause the dog's gastrointestinal acid secretion to be excessive, resulting in vomiting yellow water.