Dog gastroenteritis is inflammation of the stomach and intestines. The main symptoms are vomiting and diarrhoea, often with tiredness, a poor appetite and a sore tummy. Most mild cases settle within a day or two with rest, water and bland food, but see a vet promptly for blood, repeated vomiting, marked lethargy or a dog who will not eat.
When your dog suddenly starts vomiting or has diarrhoea, it is worrying, especially at night. The good news is that many cases are mild and short-lived. The skill is knowing which ones are not, and that is what this article is here to help with.
What is dog gastroenteritis?
Dog gastroenteritis is irritation and inflammation of the gut, mainly the stomach and intestines. It is one of the most common reasons dogs visit the vet. Think of it as your dog's version of a stomach bug or a bout of food poisoning.
It can be acute, meaning sudden and short-lived, or chronic, meaning long-term or keeps coming back. Acute diarrhoea is very common: VetCompass estimates suggest 8.18% of dogs seen in UK first-opinion practice have an episode of acute, self-limiting diarrhoea.
Key takeaway: Gastroenteritis simply means an inflamed gut. It sounds scary, but many cases settle quickly with the right care.
What are the symptoms of gastroenteritis in dogs?
The main symptoms of gastroenteritis in dogs are vomiting and diarrhoea. Look beyond the obvious, though, because other signs tell you how unwell your dog really is.
Vomit may contain food, yellow bile or blood. Stools may be loose or watery. Many dogs show tummy pain: they arch their back, seem restless or whine when their belly is touched. Some go off their food or stop drinking, which becomes a worry quickly.
Other signs include lethargy, drooling and dehydration. To check for dehydration, gently pinch the skin on the back of your dog's neck. In a well-hydrated dog it springs straight back. If it stays tented, your dog needs a vet urgently.
Some dogs bring up yellow, foamy bile first thing in the morning on an empty stomach. Our guide to bilious vomiting syndrome explains this pattern. It can be harmless now and then, but frequent bile vomiting with other symptoms can point to gastritis or acid reflux that needs a vet's help.
When should I worry about dog gastroenteritis?
Worry, and call your vet straight away, if there is blood in vomit or stool, your dog cannot keep water down, seems in pain, or is very flat. As an MRCVS-registered vet, my advice is simple: when in doubt, call.
A hunched back and reluctance to move are signs of serious tummy pain. Puppies, senior dogs and small breeds go downhill faster and need help sooner.
Call your vet if symptoms last more than a day or two, even if they seem mild. A swollen belly with retching that brings nothing up can be bloat, which is an emergency.
Increasing lethargy, a fever or confusion are also red flags. They suggest a wider illness rather than a simple upset stomach.
What causes gastroenteritis in dogs, and how is it diagnosed?
The most common cause of gastroenteritis in dogs is eating something they should not, often called "garbage gut". Scavenging on walks and raiding the bin are classic triggers.
Infections are another cause. These include viruses such as parvovirus in unvaccinated dogs, bacteria and parasites such as Giardia. Giardia can have a long tail: young dogs with Giardia gastroenteritis were more likely to have chronic gut signs (29%) and itchy skin (33%) later in life than control dogs (10% and 8%). That is one reason proper diagnosis matters.
Other triggers include a sudden change of diet, stress, some medicines, toxins, swallowed objects and conditions such as inflammatory bowel disease. The gut and brain are closely linked, so anxiety can upset a sensitive dog's stomach.
Your vet will diagnose the cause with an examination and questions about recent food, scavenging and stress. They may also suggest a poo sample test, blood tests or a scan.
How do vets treat gastroenteritis in dogs?
Vets treat gastroenteritis in dogs according to the cause and how unwell the dog is. Mild cases often need only supportive care. Severe cases may need a stay in the clinic, a drip and specific medicines.
Routine antibiotics, including metronidazole, are generally not recommended for simple acute gastroenteritis. They offer little benefit and can upset a dog's healthy gut microbiome. This is a real shift in veterinary thinking.
Instead, treatment focuses on keeping your dog hydrated, easing nausea with anti-sickness medicine when needed and letting the gut settle. Once the worst has passed, some dogs benefit from probiotics made for dogs.
For dogs who have frequent upsets, daily support can help keep digestion steady between episodes. Juno Daily for gut health combines Calsporin® Bacillus velezensis at 2 billion CFU, a spore-forming probiotic, with postbiotics: 15 billion cells of inactivated Lactobacillus that are deliberately not alive and still support a balanced gut. Chicory root, a prebiotic, feeds the friendly bacteria. If you are not sure what suits your dog, the Juno supplement quiz is a good first step.
Can I treat dog gastroenteritis at home?
You can treat mild dog gastroenteritis at home at first, as long as your dog is bright, drinking and has none of the red flags above. Safety comes first: if you are unsure, ring your vet.
Offer small, frequent meals of plain boiled chicken or white fish for sensitive stomachs, with white rice. Avoid fatty food, dairy and anything rich. Start with much smaller portions than a normal meal.
Keep your dog drinking with small amounts of water, little and often. Some dogs prefer lukewarm water or an ice cube to lick. Clean up vomit and diarrhoea with a pet-safe disinfectant, and wash your hands, to stop any infection spreading.
Keep an eye on their poo. Normal stools are firm but not hard, chocolate brown and easy to pick up. Blood, mucus or an unusual colour all need a vet.
To prevent future episodes, stop scavenging on walks with a lead and a reliable "leave it". Keep feeding times regular and change food gradually. Our guide to managing a sensitive stomach has more ideas for dogs with delicate digestion.
What are the common myths about dog gastroenteritis?
The most common myth is that every dog with diarrhoea needs antibiotics. Here are the main myths and what is really true.
Most dogs bounce back from gastroenteritis within a few days, and knowing the red flags means you can act quickly when one does not. Once your dog is back to normal, Juno Daily is a simple way to give their gut steady daily support. If anything about your dog's recovery worries you, ring your vet.
Frequently asked questions
How long does gastroenteritis last in dogs?
Most mild cases settle within a day or two with supportive care, and dogs are usually back to normal food within a few days. If symptoms last longer, get worse or keep coming back, your vet needs to look for the cause.
Is dog gastroenteritis contagious?
Sometimes. The inflammation itself does not spread, but some causes do. Parvovirus and Giardia pass easily between dogs, so keep a sick dog away from others and clean up promptly. Gastroenteritis from scavenging or stress is not contagious.
Can my dog catch gastroenteritis from me?
It is unlikely, as most human stomach bugs are specific to people. A few germs, such as Salmonella, Campylobacter and Giardia, can pass between people and dogs. Wash your hands after handling poo or vomit, and keep a poorly person away from the dog's bowls.
What should I feed a dog with gastroenteritis?
A bland, easily digested diet works best: plain boiled chicken or white fish with white rice, in small, frequent meals. Once the vomiting and diarrhoea stop, mix their usual food back in gradually over a few days.
Why does my dog keep getting gastroenteritis?
Repeated episodes usually have a cause worth finding, such as scavenging, a food intolerance, parasites, stress or a chronic condition like inflammatory bowel disease. Keep a diary of each episode and what came before it, then book a vet check.
What is haemorrhagic gastroenteritis in dogs?
It is a sudden, severe form with bloody diarrhoea, often like raspberry jam, and sometimes bloody vomit. Small and toy breeds seem more prone. Dogs can dehydrate very fast, so treat it as an emergency and see a vet straight away.
Can stress cause gastroenteritis symptoms in dogs?
Yes. The gut and brain are closely linked, and stress can speed up the gut and trigger diarrhoea in sensitive dogs. Kennels, travel, fireworks and house moves are common triggers.
What is the difference between vomiting and regurgitation in dogs?
Vomiting is active, with heaving and tummy contractions. Regurgitation is passive and often silent: undigested food or fluid simply comes back up from the food pipe. Our guide to vomiting undigested food explains why the difference matters.
This guide is for informational purposes only and does not constitute veterinary advice. Always consult your vet before making changes to your dog's diet, supplement routine, or healthcare plan.
