Just like humans, your dog may eat something that makes them sick, causing them to throw up. Vomiting one or twice a year is fairly normal, but if it becomes more frequent, prepare to take your pet to the vet. There are many reasons why your dog may be sick, not all of which have to do with diet or even the stomach. Your veterinarian will be able to help determine the problem, but these are some common causes.
Eating Something Inappropriate
Dogs, particularly puppies, are known for nosing through the trash or finding a hidden something and eating it. Eating this foreign object can irritate the stomach and intestines, causing vomiting, Much like a case of food poisoning, this sort of vomiting typically resolves on its own after 12 to 24 hours.
If the dog ate a non-food or degradable object, like socks, toys, or corn cobs, they may need to get surgery or a nonsurgical removal procedure called endoscopy.
Food Allergies
Same as humans, dogs can develop allergies to certain food products. Take a look at the average bag of dog food- there are dozens of ingredients. For some dogs with food allergies, puritus (itchy skin) is the major symptom. Other dogs with food allergies develop vomiting. Trying a new food or diet may help determine what the allergy is for.
Liver disease
Vomiting is a common symptom associated with most every flavor of canine liver disease.