Gastroenteritis (stomach upset) in dogs


  • Gastroenteritis is inflammation of the stomach and intestines, which causes symptoms such as vomiting, diarrhoea, reduced appetite, lethargy, and abdominal pain.
  • Gastroenteritis varies in severity, from mild to severe.
  • It can be caused by many different things but we don’t always find out the underlying cause, especially in mild cases that only last a couple of days.
  • Treatment tends to include medicines like anti-sickness, antacids, and probiotics, and in severe cases, a stay at the vet's for fluids and intensive care.

What is gastroenteritis?

Gastroenteritis (commonly referred to as a stomach upset) is inflammation of the stomach and intestines. The classic symptoms of gastroenteritis include vomiting, diarrhoea, stomach pain, and a loss of appetite. Gastroenteritis can vary in severity, ranging from mild (lasting one to two days with mild vomiting and diarrhoea) to severe (lasting more than two days and causing significant discomfort with frequent vomiting and diarrhoea).


If your dog has gastroenteritis, you may observe some or all of the following symptoms:

  • Diarrhoea: Gastroenteritis often presents as diarrhoea in dogs, ranging from loose stools to watery bowel movements.
  • Vomiting: or retching (heaving without bringing anything up).
  • Reduced appetite or a complete loss of appetite.
  • Lethargy (low energy)
  • A painful abdomen (tummy): Your dog may yelp or growl when their tummy is touched or if you try to pick them up. If they have severe abdominal pain they may assume a praying position (shown in the image below) with their front legs on the floor and hind legs upright.
  • Presence of blood or mucus in the stool: If your dog's stool or vomit contains a significant amount of blood, it's important to contact your vet, as it may indicate a more severe form of gastroenteritis, such as Haemorrhagic Gastroenteritis (HGE).


There are several different things that can cause gastroenteritis in dogs, such as:

Some causes, like an infection or a sudden change in diet, can lead to acute gastroenteritis, which usually appears suddenly and resolves after a few days or weeks. On the other hand, causes such as IBD and food allergies can result in chronic gastroenteritis, which tends to persist for weeks, months, or even years, with symptoms that can come and go.

When to contact your vet

Most mild cases of gastroenteritis in dogs improve within one to two days. If your dog has very mild symptoms, seems well in themselves, and is eating normally, it may not be necessary to see your vet. However, you should consult a vet if your dog experiences any of the following symptoms:

You know your dog best – if they don’t have the symptoms listed above but you are still concerned, contact your vet.


If your dog has a very mild case of gastroenteritis, it may be possible to settle their stomach at home (see advice below). Alternatively, your vet may want to see your dog to examine them, and depending on their symptoms, may recommend the following treatments:

Anti-sickness medication – to stop your dog feeling sick and vomiting. If your dog has been given anti-sickness medication and is still vomiting, it’s best to contact your vet for advice.

Antacid medications to reduce the amount of stomach acid your dog produces, which can help them feel more comfortable.

Probiotics Your vet may recommend probiotics (friendly gut bacteria) especially if your dog has diarrhoea. Probiotics contain friendly gut bacteria that are thought to help ‘reset’ the normal gut flora after a stomach upset. Many probiotics also contain ingredients to bind the diarrhoea (firm the stool) and may also help soothe the gut wall. Probiotics can be bought at your vet’s or online – where possible, use a probiotic recommended by your vet.

Antibiotics — antibiotics (medicine to treat bacterial infections) are sometimes used to treat stomach upsets, but they aren’t always necessary. Many cases of gastroenteritis aren’t caused by bacteria, so antibiotics won’t work in these cases, and can even make things worse by disrupting the “friendly” gut bacteria in your dog’s guts. If your vet does prescribe antibiotics, always follow the dosage instructions and complete the course.

Hospital treatment and a fluid drip if your dog has more serious symptoms of gastroenteritis, and/or is becoming dehydrated, they may need to stay at your vet’s for treatment. This is likely to include a fluid drip to rehydrate them and help them feel better.

Home care for dogs with an upset stomach

If your dog has mild vomiting or diarrhoea but otherwise seems fine, you can try these steps to settle their stomach at home:

  1. Small, frequent meals: Offer your dog several small meals throughout the day, spaced a few hours apart. Don't force them to eat - if they refuse food, or vomit after eating, contact your vet.
  2. Bland diet: An easy-to-digest, gut friendly diet can speed up recovery. Cooked white rice and boiled chicken/white fish (plain and without skin or bones) is an excellent option for a day or two. Or you can buy a commercially made, nutritionally balanced bland food from your vet, a pet shop, or online – these can be used for longer because they contain all the nutrients your dog needs. Avoid anything rich or fatty.
  3. Plenty of water: Ensure your dog has access to water and monitor their drinking. If they stop drinking, vomit after drinking, or drink excessively, consult your vet.
  4. Rest: Let your dog rest and avoid vigorous activity until they recover. If they have very low energy, contact your vet.
  5. Gradual reintroduction of normal food: Once your dog is feeling better and has solid stools, slowly reintroduce their regular food over a few days, starting with a mix of half normal food and half bland diet.

If your dog doesn't improve quickly, worsens, or if you're concerned, contact your vet for advice.

What if my dog doesn’t get better?

Gastroenteritis in dogs usually improves within a few days. But if your dog isn't getting better or their condition worsens, your vet may perform tests to determine the cause. These tests may include:


You can't shield your dog from all potential causes of gastroenteritis, but some sensible precautions can help:

  • Vaccination – Ensure your dog is up-to-date with their vaccinations, including parvovirus (a cause of gastroenteritis).
  • Worming Treatment – Keep your dog up-to-date with regular worming treatment.
  • Prevent Scavenging – make sure your dog can't access hazards such as food waste bins. It’s also helpful to teach a drop command so you can take away anything harmful that they pick up – check out our advice on reward-based training methods.
  • Change of diet – if you need to change your dog’s food, do it gradually over two weeks by mixing the old and new food to allow their stomach to adapt. Read our advice on how to change your dog’s food safely.


Gastroenteritis treatment can be costly, especially for severe cases requiring overnight care at the vet clinic. It's vital to discuss treatment costs openly with your vet, considering your finances and what's best for your dog.

There might be multiple treatment options, so if one doesn't suit you or your pet, your vet may suggest an alternative. Consider getting insurance for your dog early, before any signs of illness, to ensure you have financial support to care for them.

You know your dog best, always contact your vet if you’re concerned.

Published: August 2023

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Written by vets and vet nurses. This advice is for UK pets only. Illustrations by Samantha Elmhurst.