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Gastroenteritis in Dogs: When to See the Vet




Gastroenteritis – When can it be treated at home and when is it more serious?


Dogs quite commonly get ‘gastro’, or symptoms of vomiting and/or diarrhoea. The causes of gastro can range from trivial to serious. As an owner, it can be difficult to know if your dog just needs a bland diet and rest or if it needs more serious medical intervention. I understand the dilemma well because Jack (see scenario 1 below) was my dog. This was before I became a vet. I thought he just had gastro and would get better by himself...

Scenario 1: Jack, a young Cocker Spaniel, started vomiting Friday night. He vomited about ten times and had the tiniest amount of diarrhoea. After that, he seemed quite tired and wouldn’t eat dinner. The next morning, he didn’t eat breakfast and lay around for most of the next day, although he did get up for a short walk on the beach during the afternoon. That evening he still wasn’t himself. 




The owners decided to take him to the emergency centre. The veterinary staff could see straight away he wasn’t right. They booked him in for blood tests and x-rays. He had emergency surgery during the night. His large bowel had twisted and had died. His condition was inoperable. He was put to sleep on the operating table. Jack’s initial vomiting episode was the first indication that his intestines were in serious trouble when they had twisted. In this scenario, Jack needed to see a vet Friday night.

Scenario 2: Bella, a young Maltese Terrier, started having lots of diarrhoea. She also vomited a couple of times and was more tired than usual. Her main problem, though, was frequent episodes of runny diarrhoea throughout the day, sometimes with specks of blood in it. Bella had gotten into the garbage bin the previous day. On phone advice from the local vet clinic, the owners put her on a bland diet of boiled chicken and rice. She improved rapidly on the bland diet and was back to herself with in couple of days.

What is Gastroenteritis in Dogs?

Dogs don’t get the same viral gastro as humans do.

People generally use the word gastro to describe symptoms of vomiting and/or diarrhoea. Technically, the term is short for gastroenteritis, meaning inflammation of the stomach and intestines, which causes these symptoms. When using the term gastro for dogs, it is important to understand that dogs are different to humans. The most common cause of gastro in humans is viruses, particularly the noroviruses, which cause the outbreaks of gastro that spread easily from one human to another with symptoms resolving over a couple of days.

Viruses are not thought to be a common cause of gastro in dogs. Dogs are not affected by noroviruses and are protected against the main causes of viral gastroenteritis, like parvovirus, through their standard vaccinations. There are a few exceptions, like dog coronavirus, which can cause an infectious bout of gastro that usually resolves on its own. It is not a common cause of gastro in dogs but outbreaks of diarrhoea between dogs in a kennel-type environment do require further investigation.

#1. Dietary indiscretion or garbage guts

Like humans, dogs can certainly get food poisoning. In fact, dogs have evolved as scavengers and often eat undesirable things. As such, they have a well-developed vomiting reflex. Dogs will quite commonly vomit when they eat something they shouldn’t. 

It might be something irritating (like bark, rocks, sand, carpet, tampons, socks, spiders…), something toxic (like plants or chemicals), or something contaminated with bacteria or fungus (like garbage, contaminated water, or off raw bones or meat). 

Such things are common causes of inappetence, stomach pain, bloating, vomiting, and diarrhoea in dogs. 
Vets sometimes refer to this as ‘dietary indiscretion’ or ‘garbage guts’

Most cases of dietary indiscretion will resolve on their own after a few days on a bland diet of cooked chicken and rice (with no skin or bones).

#2. Food intolerance

For some dogs, it is not that they have eaten something they shouldn’t. It is just that they have a sensitive stomach. They might have an intolerance to a particular ingredient in a newly introduced food. Some dogs also don’t respond well to sudden changes in diet. 

Our latest fresh meat delivery sent one of our
dogs to the vet with gastro...
Some foods or treats out of the ordinary, especially extremely fatty or spicy foods and even sometimes the occasional raw bones or offal, can sometimes trigger gastro. 

Eating excessive amounts can also trigger a short bout of vomiting and/or diarrhoea. 

Gastro caused by food sensitivity or overindulgence is usually self-limiting. 
It will usually resolve on its own over a day or so, especially if food is withheld for 24 hours or if the dog is put on a bland diet. 

However, ongoing and intermittent bouts of vomiting or diarrhoea may require food sensitivity investigations.


#3. Intestinal parasites – worms, protozoa, bacteria

Dogs can pick up intestinal worms and other intestinal parasites (like giardia) from the ground or water, especially if they are contaminated by the faeces of other dogs or animals, like birds and rodents. 

Certain harmful gut bacteria, like SalmonellaYersiniaClostridia, and E.coli, can also be caught from eating the poo of other dogs or animals. 





Raw meat can also be contaminated with such bacteria, especially raw poultry meat. Such infections more commonly cause diarrhoea and may not resolve without specific worming medication or antibiotics. 

There is also the potential for spread to other dogs and even to humans. Dogs should be wormed every three months to prevent intestinal worms. Unless the diarrhoea is severe or the dog is very unwell, it is reasonable to see if it improves after withholding food for 24 hours then feeding a bland diet

However, a dog with diarrhoea that continues unimproved for more than a day should be checked by a vet for intestinal parasites or harmful bacteria that might require specific medication.

Is the gastro self-limiting or is it more serious?

To understand if a bout of gastro is serious or not, we need to separate the symptoms into: 

1. Predominantly vomiting and 
2. Predominately diarrhoea. 

We also need to look at the overall demeanour of the dog and how long it has been sick for. And we need to look at what it has eaten in the previous 24 hours and the events leading up to it getting sick. The exact symptoms and history tell us a great deal about what might be going on.

1. Predominantly vomiting – could potentially be more serious

The first step is to ensure that your dog is actually vomiting. It might sound silly, but a cough, retch, or regurgitation can sometimes be confused with vomiting. Vomiting is an active reflex. The reflex usually starts with some warning signals - lip licking, drooling, and repeated swallowing. Just think how you have felt prior to vomiting; It is the same for dogs. This then progresses to abdominal heaving, which culminates in intestinal and stomach contents being brought up. 

Aramis is the proverbial "garbage guts"
which has caused a few bouts of gastro...


It is worth remembering the lead-up signs to vomiting because sometimes your dog may be lip licking or drooling or even just off its food and these can be signs that your dog is nauseous even though it might not be outright vomiting.


The causes of vomiting can be deceptive. Although vomiting intrinsically involves the gut, the cause of the vomiting can originate from either inside or outside the gut. Thus, the next step is to determine which. 

Causes originating outside the gut are almost always serious and require immediate further investigation. 

For those originating within the gut itself, the next main question is if surgical intervention is required.
Common causes of vomiting originating within the gut are as mentioned previously – dietary indiscretion, food intolerances, and intestinal parasites. These are quite common causes. 
Vomiting associated with these usually lasts for only a short period of time and is commonly associated with eating. Withholding food can settle the vomiting and the dog will usually perk up during the day. 

Where the predominant symptom is diarrhoea, with only a small amount of vomiting, this also tells us the cause is probably within the gut itself and it has the potential to resolve on its own.

Vomiting without diarrhoea (or with just the tiniest amount) has the potential to be more serious. Serious causes of vomiting originating within the gut are mostly associated with blockages within the stomach or intestines. Complete blockages are life-threatening and require prompt medical intervention and often surgery. 


Common causes include foreign objects getting stuck (such as corn cobs, bones, sticks, the stones of fruits, rocks, and socks), severe constipation (most commonly after eating bones), and a twisted stomach (mostly in giant-breed dogs). Such things are diagnosed using x-rays and ultrasound. A dog with an intestinal blockage may not keep actively vomiting but will often continue to feel nauseous and look ‘seedy’. 

It will usually not eat and be lethargic and have a very painful tummy when pressed. As the problem progress, the gum colour will usually change to pale pink or brick red. Untreated, the dog will continue to deteriorate. Some of these symptoms can be difficult for owners to assess. If your dog does not pick up throughout the day after an episode of vomiting, a veterinarian is best placed to assess your dog sooner rather than later. We may need to perform x-rays or ultrasound to investigate further.

Vomiting can also commonly be sign of problems outside of the gut. The most common causes of vomiting outside of the gut are pancreatitis, liver disease, kidney disease, adrenal gland disease, diabetic ketoacidosis, electrolyte abnormalities, and diseases within the ear or brain. But there are many other causes as well. 

All these conditions are serious and require prompt investigation. 




Usually there will be some warning signs in the days leading up to vomiting, such as an increase in thirst, lethargy, changes in eating habits, and weight loss for example. Except for pancreatitis, the vomiting caused by problems outside of the gut will often occur randomly and not be associated with eating. 

Pancreatitis is a potentially life-threatening inflammation of the pancreas, often triggered by a fatty meal. Pancreatitis usually causes vomiting after eating. Dogs may also vomit immediately following a snake bite. If you suspect a snake bite, seek vet care immediately. All these conditions require timely further investigation, usually starting will a comprehensive blood test.

2. Predominantly diarrhoea – usually a gut-specific issue

Diarrhoea is quite common. Unlike vomiting, the causes of diarrhoea are most commonly within the gut itself. The most common causes of sudden diarrhoea are as mentioned previously, particularly dietary indiscretion, food intolerances, intestinal parasites, and overeating. Even stress can cause diarrhoea in some dogs. Non-severe diarrhoea does not usually require investigation and it usually responds well over a couple of days to merely withholding food or a bland diet.

Eddie lost its battle with Parvo during
an outbreak in Northern NSW early 2020
Photo Credit: Paws for a Purpose
Some cases of sudden diarrhoea do require prompt veterinary care. Any young puppy that is not fully vaccinated and has lethargy, vomiting, or diarrhoea should get tested for parvovirus, a potentially life-threatening illness

Severe diarrhoea, from any cause, in a puppy less than 6 weeks of age should also prompt veterinary care, since younger animals are more prone to dehydration.

Haemorrhagic gastroenteritis is a severe, potentially life-threatening and poorly understood cause of diarrhoea, causing profuse amounts of frank blood to spurt from the bottom. Dogs with this condition can lose too much blood and go into shock. They require prompt medical treatment.

Diarrhoea can sometimes follow the ingestion of certain toxins. If the poo contains a brightly-coloured foreign substance that could be a toxin or if you know your dog has ingested a known toxin (like snail bait, rat bait, borax, fertilizer, ibuprofen, chocolate) or overdosed on medication, you should seek prompt medical care to limit the toxin from causing other issues internally.

Much less commonly, diarrhoea can be associated with severe disease outside of the gut, such as pancreatitis or adrenal disease. In these cases, the dog will usually be quite sick and there will also often be vomiting. Such dogs require prompt veterinary care.

In general, you should also seek veterinary care if the diarrhoea persists despite treatment, if it is severe, if it is leading to weight loss or dehydration, or if the dog generally seems quite unwell.

Chronic, ongoing diarrhoea is also quite common in dogs. There are many causes, including infections, food allergies, intestinal worms, parasites, inflammatory bowel disease, and cancer. Diarrhoea that continues unimproved for more than a couple of days or intermittent episodes of vomiting or diarrhoea without an obvious cause (such as frequent garbage eating, should be investigated further.

Specific signs for when to see your vet sooner rather than wait?

It can be hard as a veterinarian to relay all the information and symptoms we are using to assess whether a dog requires further investigation and treatment for gastro. If your dog is generally well, if the symptoms are mild, and if you know what likely triggered the symptoms (like your dog raided the garbage bin), then it is reasonable to see if your dog’s symptoms will respond to withholding food or a bland diet. 

However, in general, you should seek veterinary care:

1. If your dog is very lethargic and not responding well to you

2. If the diarrhoea is profuse or continues without improving for more than a day

3. If your dog is spurting lots of frank blood from its bottom

4. If your dog has excessive drooling

5. If the vomiting or nausea is relentless or is continuing all day

6. If your dog does not improve or pick-up after the vomiting ceases

7. If there are other symptoms, like very pale, yellow, or brick red gums

8. If your dog has been unwell for several days prior

9. If you know your dog ate a sock/bone/corn cob/rock etc. and is now vomiting

10. If you know your dog ate a toxin or overdosed on medication

11. If you have an unvaccinated dog, especially a puppy

12. If you are worried and want reassurance

13. If you want to see if there is symptomatic treatment available

Seek Immediate Care:

1. If there is vomiting, lethargy, and severe tummy bloating, especially in a large breed dog

2. If vomiting could be associated with a snake bite


Written by Dr Meredith Crowhurst, January 2021 for Australian Dog Lover (all rights reserved).

About Dr. Meredith Crowhurst

Dr Meredith Crowhurst is a Melbourne-based locum veterinarian. Melbourne University graduate with more than a decade of experience, she has extensive consultation and surgical experience and has worked with dogs, cats, rabbits, guinea pigs, rats, mice, birds, and various other animals.

Meredith understands the importance of the human-animal bond. Her aim is to treat pets and their owners with empathy and compassion, delivering the best standard of care.

Previously, Meredith completed a Bachelor of Arts/Bachelor of Science degree and completed her PhD in the biomedical sciences. As well as treating animals, Meredith’s aim is to educate and make medical science knowledge accessible for all


You can contact her at www.empathichealthwriting.com.au/ and follow her on Instagram at instagram.com/drmerryoliveveterinarian
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