If your pit bull vomits occasionally then no need to worry. Dogs can vomit almost daily without any harm. If your dog is vomiting along with loss of appetite, lethargy and diarrhea then its medical emergency and requires vet visit. Vomiting in dogs can be symptom of many diseases and conditions like gastrointestinal diseases including intestinal parasites, food and chemical allergies, ear infections and many other diseases. If your dog is vomiting along with other signs of illness then take him to vet for diagnosis and advice.