Causes
Acute: ingestion of something irritating, spoiled food, eating too fast. Chronic: long periods of fasting, food allergies, medications, underlying conditions.
Diagnosis
Clinical history. If chronic or severe, the vet will investigate further with blood tests, ultrasound or endoscopy.
Treatment
Mild cases: a short fast, a bland diet, small and frequent meals. Chronic cases: identify and treat the cause. The vet will advise whether a gastric protectant is needed.
Prevention
Spread out meals to avoid long fasts, a good-quality diet, gradual changes, avoid human leftovers.

