It is best to fast for half a day or a day if your dog vomits yellow water. At the same time, you should also observe whether the dog has other symptoms. If the dog has vomiting, diarrhea, poor energy, loss of appetite, blood in the stool, etc., it is best to take the dog with you. The dog should go to the pet hospital for examination to avoid delaying the condition; if the dog has no other symptoms, it may be caused by improper diet or indigestion. You need to help the dog adjust its diet, and then feed the dog some probiotics to regulate the intestinal tract.