When Diarrhea Turns Dangerous for Dogs

Understanding hemorrhagic gastroenteritis symptoms including sudden vomiting and bloody diarrhea
By Shea Cox DVM, February 2012, Updated June 2020
This HGE-sufferer with bloody diarrhea a dog. The dog named Sam made a full recovery.

One of the more common dog problems I see on an emergency basis is a disease in dogs called hemorrhagic gastroenteritis, also known as HGE. I recently treated Sam, the little Beagle in the photo, for a severe case of this disease.

The history I hear from owners is always the same: “My dog started having diarrhea and then, all of a sudden, it became very watery and bloody.” This can be horrifying to first-time observers and usually prompts a trip to the ER.

Symptoms of HGE in Dogs

Hemorrhagic gastroenteritis is a potentially life-threatening intestinal condition, which manifests as a sudden onset of watery, bloody diarrhea in dogs, with vomiting often being part of the syndrome. Sloughing of the lining of the intestines occurs from severe inflammation leading to “chunks” of tissue in the otherwise watery stool.

We describe this as “raspberry jam” or jelly like bloody diarrhea. When this happens it is extremely dehydrating for the dog—much more than you would think from the amount of diarrhea observed—and dogs can go from “near normal” to “near death“ in a frighteningly short time. If HGE is not promptly treated, the massive loss of fluid can cause life-threatening shock.

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Thankfully, there are no long-lasting bodily effects of HGE, however, some dogs that have sensitive GI tracts to begin with can have the syndrome recur in the future.

What causes HGE?

Stress, sudden dietary changes and hyperactivity seem to be predisposing factors, but the actual cause of this disease remains unknown. A bacterium called Clostridium is also thought to play a role. In short, the condition is truly another medical mystery, and I can relate to an owner’s confusion and frustration when they ask, “Yeah, but what actually caused it?” I cannot point to an exact cause in more than 80 percent of HGE cases I treat.

Smaller dogs seem to have a predisposition towards 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 a larger dog; it simply doesn’t take much diarrhea for them to become severely dehydrated. 

How is HGE diagnosed?

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

When the patient becomes very dehydrated, there is less fluid in the bloodstream and the percentage of blood fluid drops, and consequently the percentage of red blood cells increases. A dog with HGE will generally have a PCV greater than 60 percent.

The measurement of the PCV also includes a measurement of total protein (sometimes called total solids). In HGE, the total protein measurement from the blood sample is low or normal.

A very high PCV, low total protein and acute onset bloody, watery diarrhea can point to a diagnosis of HGE.

From a medical standpoint, one of the things that makes diarrhea difficult is that no matter what the underlying cause, the clinical picture looks exactly the same. Because of this, we may still recommend that additional tests, such as radiographs, a fecal exam (that includes a parvovirus test) and blood work, be performed to make sure there is not a more serious problem causing the clinical signs.

Hemorrhagic gastroenteritis really becomes a diagnosis of exclusion: When blood work, radiographs and fecal exams are normal, we highly suspect HGE as the cause.

What is the treatment for HGE?

The heart of therapy is very aggressive fluid replacement with intravenous fluids. The goal is to get the packed cell volume back to the normal range and keep (or get) the patient out of shock. Food is withheld for at least 12 to 24 hours and then gradually introduced after the vomiting has resolved. Symptomatic treatment for nausea and belly discomfort is typically included, as is antibiotic therapy. One to three days of hospitalization is commonly required for treatment.

With early and aggressive treatment, life-threatening complications are generally avoided and dogs return happily home. In the case of Sam, he unfortunately required four days of intensive care, including nutritional support through a feeding tube as pictured, but I am happy to report that he made a full recovery and went back home to Mom and Dad!

Shea Cox earned a veterinary medical degree from Michigan State University in 2001 and has been practicing emergency and critical care medicine since. In 2006, she joined PETS Referral Center. In her spare time, she loves to paint, wield her green thumb and cook up a storm. She shares her days with the three loves of her life: her husband Scott and their two Doberman.