Causes
Many: a sudden change of diet, ingestion of something spoiled or toxic, parasites, viral or bacterial infections, stress, intolerances.
Diagnosis
Clinical history and physical examination. If severe or prolonged: blood tests, faecal analysis, ultrasound or X-ray to rule out serious causes.
Treatment
Mild cases: a short fast, a bland gastrointestinal diet, hydration. Severe cases: fluid therapy, anti-emetics, treatment of the underlying cause. Do NOT self-medicate — some human medicines are toxic.
Prevention
Make dietary changes gradually (7-10 days), don't give food leftovers, keep deworming up to date, prevent access to rubbish.

