The most common cause of vomiting in dogs is dietary indiscretion (eating something inappropriate or a sudden change in diet). Other common causes of vomiting in dogs are ingestion of a foreign body, travel sickness, and infectious parasitic and viral diseases. Vomiting may also be caused by a serious underlying medical condition. First aid will help to calm your dog's stomach down until professional help is received. Puppies can be come very sick and even die if their vomiting is not immediately addressed. Do not wait to call the veterinarian if a puppy is vomiting.