Gastritis means inflammation of the stomach lining. It is a description rather than a diagnosis, and the useful question is always what is causing it.

Acute gastritis

Comes on suddenly. Repeated vomiting, drooling, lip licking, loss of appetite, and often a dog that eats grass and stands with its front end lowered and its rear raised, a posture that suggests abdominal discomfort.

The usual cause is dietary indiscretion: bin raiding, scavenging on a walk, a sudden change of food, or something rich and fatty from the table.

Most acute cases settle within one to two days with simple treatment.

Chronic gastritis

Intermittent vomiting over weeks or months, often with weight loss, a dull coat and reduced appetite. This one needs investigating rather than repeatedly treating.

Causes include food intolerance, inflammatory bowel disease, intestinal worms, chronic kidney disease, liver disease, medication, and less commonly tumours.

Medication as a cause

Worth stating plainly: human anti-inflammatory painkillers are a common cause of gastric ulceration in dogs. Ibuprofen, aspirin and diclofenac damage the stomach lining and can cause bleeding ulcers and kidney failure. Never give them to a dog.

Even veterinary anti-inflammatories can irritate the stomach, which is why they are given with food and why we ask you to stop them and call if vomiting starts.

What we do

We examine the dog and assess hydration first. Where the history points to something acute and the dog is otherwise well, treatment is usually straightforward: fluids, an anti-sickness injection, gastric protection and a bland diet for a few days.

Where vomiting is chronic, or there is weight loss or blood, we investigate: blood count, biochemistry, faecal testing, imaging, and in some cases endoscopy or biopsy.

At home

Small portions of a bland, low fat food several times a day rather than one large meal. Fresh water always available, offered in small amounts frequently if large drinks come straight back. No treats or table food during this period. Return to the normal diet gradually over several days.

When to come in

Vomiting that continues beyond a day. Blood in the vomit, or material like coffee grounds. Black tarry faeces, which indicate digested blood. A dog that cannot keep water down. Lethargy, pale gums or a painful abdomen. Repeated episodes over months.

And the one that must not wait: retching without producing anything, in a dog with a swollen, tense abdomen. That is gastric torsion, not gastritis, and it is an emergency.