If your dog suddenly vomits, it could be the simple result of eating too fast, exercise straight after eating or motion sickness. It could also be an indication of stomach problems such as gastritis, brought on by eating spoiled foods, garbage or toxins. However, it could also be a sign of infection or disease. 

If your dog is persistently vomiting, or even sporadically, but over a lengthy period, get him checked by a vet. If he vomits blood, get him to the vet immediately. Acute vomiting could be a sign of one of the following: canine parvovirus, pancreatitis, kidney or liver failure, diabetes mellitus, Addison's disease, Cushing's disease, parasites, diseases of the inner ear, stomach or upper intestinal cancer

If your dog is a puppy, older, or has pre-existing medical problems, see your vet immediately. But if your dog is alert and active and has had no previous health problems, you may want to try the following treatment at home before consulting your vet. Withhold food and water for at least six hours. If the vomiting stops, give your dog ice cubes to lick every three to four hours, then gradually increase the amount of water. After 6 hours without vomiting, give your dog small amounts of a bland low-fat food several times a day for a few days. Little by little, you can increase the amount back to your dog's normal diet.

Some of the more common signs your dog will show include feeling anxious and restless, coming to you for attention and comfort, drooling and swallowing repeatedly just before vomiting.

Not to be confused with regurgitation, which is a relatively effortless ejection of undigested food from the oesophagus, vomiting is a forceful ejection of stomach and upper intestine contents. It smells sour and contains partially digested foods and yellow bile. More often than not, when your dog vomits, it’s a reaction to a minor stomach upset. However, you need to know the signs in case it’s due to something more serious.