Dog vomiting occurs when the dog's stomach contents are expelled through the mouth. Vomiting may be caused by a variety of things, including motion sickness, eating too fast, eating something that disagrees with the dog, or a viral or bacterial infection. Treatment for vomiting depends on the cause. If the dog is vomiting due to an infection, antibiotics may be prescribed. If the dog is vomiting due to motion sickness, the dog may be given medication to help with the nausea. If the dog is vomiting for no apparent reason, the dog may be given medication to stop the vomiting. Prevention of vomiting includes feeding the dog small meals, not allowing the dog to eat too fast, and avoiding foods that the dog is allergic to.