HGE in Dogs: Causes, Symptoms and Treatment

Certain symptoms could mean your dog is battling a potentially fatal condition called haemorrhagic gastroenteritis (HGE). Here’s everything you need to know

by Dr. Shea Cox, DVM, CVPP, CHPV | expert review by Dr Grace Mee

Updated February 10, 2026

As a vet, one of the more common emergencies I see in dogs is a gastrointestinal (tummy) condition called haemorrhagic gastroenteritis, also known as HGE. When pet parents rush their dogs in for treatment, the story I hear is always the same: “My dog started having diarrhoea and then, all of a sudden, it became very watery and bloody.” Vomiting can also play a part, leaving some dogs dehydrated and fighting for their lives. This can be horrifying to first-time observers, but how does it happen and what does it mean? Let’s break that down.

What is HGE in dogs?

Haemorrhagic gastroenteritis (HGE) is a serious condition in dogs that can cause bloody diarrhoea, vomiting and dehydration. It is also often referred to as AHDS (Acute Haemorrhagic Diarrhoea Syndrome). The exact cause of this is unknown, but it is thought to be triggered by a combination of factors, including stress, diet and infection. Dogs of all ages and breeds can be affected by HGE, but it can hit young, small-breed dogs the hardest. If you think your dog may have HGE, it is important to seek veterinary care immediately. HGE can be a life-threatening condition, but with prompt treatment, many dogs make a full recovery within a few days.

What are the symptoms of HGE in dogs?

Haemorrhagic gastroenteritis manifests as a sudden onset of watery, bloody diarrhoea in dogs and sometimes vomiting.

Their diarrhoea can have a ‘raspberry jam’ or jam-like bloody consistency. When this happens, it is extremely dehydrating for the dog – much more than you would think from the amount of diarrhoea observed. Dogs can go from near-normal to near-death in a frighteningly short amount of time.

How much do you spend on your pet per year?

Thankfully, when HGE is fully treated, there are usually no long-term health impacts. However, some dogs with sensitive GI tracts can have similar episodes in the future.

What causes HGE in dogs?

HGE is a bit of a medical mystery. I understand a pet parent’s confusion and frustration when they ask, “But what actually caused it?” More than 80 percent of the time, I can’t point to an exact cause. It is thought that stress, sudden dietary changes and bacterial hypersensitivity (especially to Clostridium) are predisposing factors.

One thing’s for sure though. Smaller dogs seem to be more vulnerable to HGE, and it should be noted that the smaller the dog, the more dangerous the condition. Small dogs just don’t have the same bodily reserve as larger dogs; it doesn’t take much diarrhoea or vomitting for them to become severely dehydrated.

How is HGE in dogs diagnosed?

There are no specific tests for HGE, but one called a packed cell volume (PCV) test is helpful in narrowing down the diagnosis. Using a few drops of blood, it measures the percentage of blood volume made up by red blood cells. A normal packed cell volume for a healthy dog is between 37–55 percent, meaning that percentage of blood volume is red blood cells and the rest is fluid and white blood cells.

When a dog becomes very dehydrated, the percentage of blood fluid drops due to less fluid in the bloodstream, usually causing the percentage of red blood cells to increase. A dog with HGE will generally have a PCV greater than 60 percent.

A PCV test also gathers a measurement of total protein (sometimes called total solids) from the blood sample, which, in HGE patients, is usually low or normal. So a very high PCV, low total protein count and acute onset bloody, watery diarrhoea (and often vomiting) all point to an HGE diagnosis.

Even with the PCV test, because diarrhoea in dogs can have so many causes, additional testing such as radiographs, a faecal exam (that includes a parvovirus test) and blood tests may be recommended to rule out other issues. HGE really becomes a diagnosis of exclusion: when all other tests are normal, we highly suspect HGE as the cause.

How is HGE treated?

The heart of therapy for HGE is prompt fluid replacement with intravenous fluids. The goal is to get the packed cell volume back to the normal range and keep (or get) the dog out of shock. Gastrointestinal or bland food is offered, along with pain medication (for belly discomfort) and supportive anti-nausea medication may be given if a dog’s appetite is negatively affected too. Antibiotics are generally not necessary for mild-moderate cases, unless there is a low white blood cell count or evidence of sepsis. Typically dogs are hospitalised for 1-3 days, but this duration may be longer for severe cases.

With early treatment, life-threatening complications of HGE are generally avoided and dogs happily return home.

What are the best practices for preventing HGE in dogs?

Since the cause is still unknown, it is difficult to give advice on prevention of HGE in dogs. Feeding your dog a consistent, high-quality, healthy diet, not giving them food they‘re not used to, and using parasite preventive medications as recommended by your vet may help prevent HGE.

How can I support my dog’s recovery after HGE?

First and foremost, follow your vet‘s recommendations for helping your dog recover from HGE. They will likely include doing things like giving your dog prescribed medications, giving them the space and time to recuperate – make sure they have a comfortable place to rest and monitor them for symptoms such as vomiting and diarrhoea. If they return, take your dog back to the vet ASAP.

Frequently asked questions

Can HGE recur in dogs?

When HGE is fully treated, there are usually no long-term health impacts. However, some dogs with sensitive GI tracts can have episodes in the future.

Can you treat HGE in dogs at home?

No, it is inadvisable to treat your dog for HGE at home. The disease requires immediate medical attention and potential hospitalisation. Take your dog directly to the vet.

Can HGE be fatal?

Yes, unfortunately HGE can be fatal. It’s essential to get your dog to a vet quickly to get medical treatment.

References

Dr. Shea Cox, DVM, CVPP, CHPV

Dr. Shea Cox is the founder of BluePearl Pet Hospice and is a global leader in animal hospice and palliative care. With a focus on technology, innovation and education, her efforts are changing the end-of-life landscape in veterinary medicine.