Gastritis in dogs: symptoms and treatment

Overview

Acute gastritis is often brief and may settle within 24 hours. If symptoms resolve quickly, the precise cause is usually not established. Chronic gastritis may be suspected when vomiting persists or recurs for more than one to two weeks without another obvious explanation.

Stomach inflammation may be the only gastrointestinal abnormality or part of a wider disease. Chronic gastritis subtypes are distinguished by the inflammatory cells seen in mucosal biopsies. In atrophic gastritis, the lining thins and its glands shrink.

The stomach lining's defences weaken as inflammation damages surface cells. Inflammation may appear on endoscopy as a superficial erosion, or surface damage to the lining.

Causes

Acute inflammation can begin after eating spoiled food or rubbish. A swallowed foreign body can irritate the stomach lining. Some plants and chemicals can also damage the stomach. Stomach wall inflammation can activate the vomiting reflex through the nervous system.

Stomach symptoms may relate to disease elsewhere, such as pancreatitis. Physaloptera worms are one possible cause of canine gastritis. Food hypersensitivity is a possible underlying factor in chronic gastritis. Helicobacter bacteria also occur in healthy dogs' stomachs, so finding them does not establish the cause of vomiting.

In lymphoplasmacytic gastritis, lymphocytes and plasma cells accumulate in the stomach lining. In the eosinophilic form, eosinophils, a type of white blood cell, particularly accumulate in inflamed areas. Skin symptoms alongside eosinophilic gastritis may raise suspicion of food hypersensitivity.

Risk factors

Dogs eating rubbish or other foreign material have a greater risk of stomach irritation. Non-steroidal anti-inflammatory drugs, or NSAIDs, can predispose to stomach lining damage. They can weaken mucosal protection by reducing protective prostaglandin production. Liver disease is associated with an increased risk of stomach or duodenal ulceration.

A breed-specific form of chronic atrophic gastritis is recognised in Norwegian Lundehunds. They also develop Lundehund syndrome associated with dilated small-intestinal lymphatics, which can involve intermittent vomiting.

Ulcer risk increases when a dog receives an NSAID alongside a corticosteroid. Older, small male dogs more commonly develop gastropathy causing thickening around the pylorus.

In intensely competing sled dogs, strenuous exercise can be associated with stomach surface lesions. After a long sled-dog race, gastric erosions, ulcers or bleeding were found in 48% of 70 examined dogs. They had not undergone endoscopy before the race, so when the lesions developed remained unknown.

Typical symptoms

Acute gastritis typically starts with vomiting, sometimes without warning signs. Chronic gastritis may cause intermittent vomiting of food or bile despite improvement between episodes.

• Reduced interest in food or refusal to eat.
• Tenderness when the front of the abdomen is felt.
• White foam or yellowish bile in vomit.
• Swallowed material, such as grass or bone fragments, in vomit.
• Unusual tiredness or dullness.

Pain in the front of the abdomen may cause a posture with the chest and forelegs near the floor but the hindquarters raised. Weight loss is not typical of mild chronic inflammation confined to the stomach and may suggest more extensive gastrointestinal disease.

If pyloric narrowing impairs stomach emptying, food may be forcefully vomited hours after a meal. Among 82 dogs investigated for stomach or duodenal ulcers, 32% vomited blood. Black, tarry faeces occurred in 31% of these ulcer patients.

Complications and consequences

Repeated vomiting can dehydrate a dog enough to need intravenous fluids. Stomach surface damage can extend deeper and form an ulcer. Gastrointestinal bleeding can cause anaemia. A severely bleeding or perforated ulcer can cause shock.

An ulcer extending through the stomach wall can cause peritonitis. Atrophic gastritis in Norwegian Lundehunds carries an increased risk of gastric adenocarcinoma. Severe thickening around the pylorus can prevent food leaving the stomach normally.

Blood mixing with stomach or small-intestinal contents can turn faeces black as it is partly digested. A perforated ulcer can allow gas into the abdominal cavity. An ulcer can be significant even without vomiting blood or black faeces.

Diagnosis at the vet

History and initial investigations

The vet assesses possible acute gastritis from symptoms, history and examination findings. If symptoms do not improve within two days of supportive treatment, further investigation is needed. Chronic vomiting investigations often include a blood count, biochemistry and urine testing. Routine blood tests may be normal despite chronic gastritis.

Faecal testing can investigate parasites as a possible cause. Cortisol measurement or an ACTH stimulation test may be needed to investigate hypoadrenocorticism. In one emergency study, the cause of vomiting remained unknown in 39 of 99 dogs. Abdominal ultrasound was more useful when symptoms had lasted longer or appetite was reduced.

Imaging and biopsies

Abdominal X-rays can look for signs of a swallowed object or intestinal obstruction. Ultrasound examines stomach wall structure. A non-perforated stomach ulcer may be missed on ultrasound. Imaging can sometimes also identify a tumour, enlarged lymph node or narrowed pylorus.

Gastroscopy shows whether the lining has redness, swelling or ulcers. Chronic gastritis is confirmed by microscopic examination of stomach biopsies. In one endoscopic study, 110 stomach and duodenal samples were examined from 22 symptomatic dogs.

Disease involving deeper stomach wall layers may require a surgical biopsy for diagnosis. Helicobacter can be sought in brush or tissue samples taken during endoscopy.

A chronic stomach ulcer can resemble a tumour on endoscopy, so tissue sampling is needed to distinguish them. If an ulcer needs sampling, the vet takes it from the edge to reduce perforation risk. Helicobacter in a biopsy may be incidental, particularly without significant mucosal inflammation.

Treatment

Supportive care for acute gastritis

Treatment aims to control vomiting and replace lost fluid. The vet may also treat pain if the front of the abdomen is tender. Mild dehydration of less than 5% can sometimes be corrected with subcutaneous fluids. If a dog is dehydrated and still vomiting, fluids need a route other than the mouth.

Once vomiting is controlled, a small amount of water can be tried. Food can initially be given in small portions if the dog can eat. Normal feeding is resumed gradually over three to five days if recovery progresses. Most dogs with acute gastritis recover with supportive care within one to three days.

The vet considers possible obstruction before choosing an anti-nausea medicine that promotes gut movement. A feeding tube may be needed if the dog cannot eat enough independently.

Persistent inflammation and ulcer treatment

For persistent gastritis, a dietary trial can assess whether new food improves symptoms before more invasive investigations. Highly digestible food may be sufficient as part of supportive care for mild chronic inflammation. Biopsy-confirmed moderate or severe inflammation may need immunosuppressive medication. If small-intestinal disease is also present, cobalamin deficiency can be treated with supplementation.

Acid-suppressing medication can promote healing of a confirmed stomach ulcer. Without mucosal erosion, a benefit from precautionary gastroprotective medication has not been established. Acid suppression does not replace treatment of nausea. A perforated stomach ulcer needs surgery.

Finding Helicobacter does not automatically lead to antibiotics. If an ulcer is associated with an NSAID, the vet assesses stopping it. The outlook is better when the cause can be removed and the ulcer is superficial.

For a confirmed ulcer, proton pump inhibitors suppress stomach acid more effectively than histamine receptor blockers. Obstructed emptying caused by pyloric narrowing can sometimes be relieved surgically.

Prevention

Keeping rubbish and spoiled scraps out of reach reduces the risk of eating unsuitable food. Do not leave fruit stones accessible: swallowing one can obstruct the digestive tract. Keeping human and animal medicines in a closed cupboard helps prevent accidental ingestion.

Using two different NSAIDs together increases gastrointestinal adverse effects. Do not give a dog a human NSAID on your own. Gastrointestinal adverse effects can also occur in a dog that was healthy before starting an NSAID.

Mention any previous stomach ulcer before an NSAID is prescribed. Do not start medication left over from another dog on your own.

Important for dog owners

Record when vomiting began and how many times it occurred. Mention access to rubbish or possible swallowing of medication or an object. Monitor drinking: vomiting fluid back makes dehydration harder to correct at home. Black, tarry faeces can suggest upper gastrointestinal bleeding.

If a dog taking an NSAID begins vomiting, stop giving it and contact the vet. Record appetite changes and other new symptoms to help the vet assess the overall picture. Contact the vet if symptoms return after settling.

If you suspect harmful ingestion, establish what the substance was and how much was eaten. When NSAID treatment is assessed, mention other prescription and non-prescription medicines too.

Frequently asked questions

Does every episode of vomiting mean gastritis?

Vomiting can also result from intestinal obstruction or hypoadrenocorticism, for example. Assessment of acute gastritis often relies on history, examination and response to supportive care. Recurrent vomiting may need imaging even if initial blood tests are normal.

What can stomach bleeding look like?

Vomit may contain fresh blood or blood partly digested in the stomach. Black, tarry faeces can indicate upper gastrointestinal bleeding. With heavy bleeding, a dog may be weak and have pale mucous membranes.

Does a chronically vomiting dog always need endoscopy?

Tests are chosen according to the history, clinical examination and any other symptoms. Imaging often checks for another abdominal explanation before endoscopy. If chronic gastritis needs confirmation, the vet requires stomach lining biopsies.

Does Helicobacter always need treatment?

Helicobacter can occur in the stomach lining of a completely healthy, symptom-free dog. Its significance is assessed partly by whether biopsies also show clear gastric inflammation. Even if vomiting improves during treatment, bacteria may still be found later.

Can I give my dog medicine from my own cupboard?

Do not give human painkillers to a vomiting or apparently painful dog on your own. NSAIDs can irritate the stomach lining. If the dog already receives an NSAID, adding another increases gastrointestinal risks.