When Diarrhea Turns Dangerous for Dogs

As a vet, one of the more common emergencies I see in dogs is a stomach condition called hemorrhagic 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 diarrhea 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 Are the Symptoms of HGE in Dogs?

Hemorrhagic gastroenteritis manifests as a sudden onset of watery, bloody diarrhea in dogs and sometimes vomiting. It’s a shedding of the intestinal lining due to severe inflammation and is often identified by “chunks” of tissue in otherwise watery stool.

We describe those chunks 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 amount of time. 

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

What Causes HGE in Dogs?

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 reality, though, it’s kind of a medical mystery. And I can relate to a pet parent’s confusion and frustration when they ask, “Yeah, but what actually caused it?” Because more than 80% of the time, I can’t point to an exact cause.

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 simply doesn’t take much diarrhea 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 and 55%, 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%.

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 in conclusion, a very high PCV, low total protein count, and acute onset bloody, watery diarrhea all point to an HGE diagnosis.

Even with the PCV test, because diarrhea in dogs can have so many causes, additional testing such as radiographs, a fecal exam (that includes a parvovirus test), and blood work 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 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 dog out of shock. Food is withheld for at least 12 to 24 hours and then gradually introduced after any vomiting has subsided. Symptomatic treatment for nausea and belly discomfort is typically included, as is antibiotic therapy, all of which is carried out within a one to three day hospitalization.

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