Vomiting is a very unspecific sign. It could acute or chronic. It can be caused by disorders from the digestive system (primary gastrointestinal disorders), or outside the digestive system ( extra-gastrointestinal disorders). They could be just a dietary intolerance ( change in diet),  certain medication, or a life threatening twisted stomach (gastric dilatation/volvulus),  an obstruction in digestive system, diabetes mellitus, kidney failure, liver failure or a pancreatitis etc. Once you notice your pet is vomiting, food and water should be withheld for 12 hours. Further investigation by your veterinarian should be done as soon as possible to find the primary disorders that caused the vomiting.  As mentioned above, some of the underlying causes could just be a change of the diet, but some of them may be a life threatening disease or could potentially develop into a life threatening situation. For further diagnoses, a blood test, urine analysis, or imaging (X ray, ultrasound) may be needed. It will also depend on the other clinical signs your pets are showing, the result of the physical examination, breed, age, and sex of your pets. The treatment of vomiting should not be just about controlling the vomiting, but more importantly, primary disorders that caused the vomiting should be found out and treated promptly. For more details based on the case, please talk with your veterinarian.