A dog might vomit for a variety of reasons, ranging from eating too quickly, to more serious injuries or illness, according to WebMD. Sudden episodes may be due to a food intolerance, while chronic episodes may stem from an obstruction in the gastrointestinal tract. If the dog only vomits once, then resumes normal eating and behavior, the cause is likely to be minor stomach upset, however, if vomiting is frequent or accompanied by blood, diarrhea, dehydration, lethargy, weight loss or appetite change, consult a veterinarian to schedule a thorough check-up.
Isolated incidents are probably not serious, but longer or reoccurring episodes can be symptomatic of serious illness or infection. Vomiting that lasts for more than one day or occurs more than once a day is also cause for concern. While WebMD suggests following a veterinarian's advice, the site also recommends feeding the dog soft, bland foods which help to steady the dog's stomach. Boiled potatoes, rice and chicken breast are all advised.
petMD notes that a dog can indicate its desire to vomit by drooling, licking its lips and swallowing excessively. Some dogs may eat grass to induce vomiting, in order to expel something unwanted from their stomachs. petMD also differentiates between vomiting and regurgitation, as the latter occurs without effort as undigested food spontaneously rises.