Occasional vomiting is not unusual in dogs, however, chronic vomiting indicates there is an underlying disease process. There are many causes of chronic vomiting and may include dietary indiscretion, dietary intolerances, infection, drugs, toxins, obstruction or blockage of the gastrointestinal tract, metabolic diseases such as liver or kidney disease, inflammatory bowel disease, ulcers, and cancer. Your vet will need to take a thorough history of the problem, do a full physical examination and further tests like blood tests, faecal tests, urine tests, and radiographs may be necessary in order to investigate the underlying cause of the vomiting. If left untreated, chronic vomiting causes malnutrition, dehydration and electrolyte imbalances. For the welfare of your animal it is important that the cause of these signs be addressed.