Hemorrhagic gastroenteritis (HGE in dogs), which is also called acute hemorrhagic diarrhea syndrome (AHDS in dogs), is a condition where dogs suddenly develop profuse bloody diarrhea and can quickly become dehydrated. Integrative veterinarian Dr. Julie Buzby explains the symptoms, causes, diagnosis, treatment, and prognosis for HGE so dog parents can be informed about this potentially life-threatening problem.
I’ll never forget the morning a frantic client rushed into our clinic carrying her Miniature Schnauzer, Daisy, wrapped in a towel. She had been perfectly fine the night before—playful, hungry, full of energy. But that morning, Daisy suddenly began vomiting and passing what looked like pure blood. Things worsened throughout the afternoon. By the time she entered my office, her owner was convinced she was losing her.
Fortunately, by this point in my career, I had seen these signs before. After I performed a quick exam and gathered a history, I shared my suspicion that this sweet Schnauzer was suffering from a relatively common condition known as hemorrhagic gastroenteritis (HGE).
What is HGE in dogs?
Hemorrhagic gastroenteritis (HGE) is a condition in dogs characterized by rapid-onset, profuse bloody diarrhea, which may look like raspberry jam or straight blood. Affected dogs can become severely dehydrated and often vomit, too.
The symptoms are dramatic and can appear seemingly out of nowhere. Left untreated, HGE can be fatal, but thankfully, with prompt veterinary care, most dogs recover quickly and completely.
Veterinarians have adopted a newer name for the same condition—acute hemorrhagic diarrhea syndrome (AHDS). This updated term helps clarify that this condition primarily affects the intestines (rather than using the word “gastroenteritis”, which refers to the stomach and intestines). And it emphasizes how abrupt and severe the signs can be.
Veterinarians are creatures of habit, however, so many have stuck with the older “HGE” terminology. That is what I will primarily use in this article, too.
What are the symptoms of HGE in dogs?
One of the most frightening things about the condition is how suddenly symptoms of HGE appear. Many dogs seem perfectly fine one day and extremely sick the next. The common signs of HGE include:
- Vomiting: In more than half of the cases, dogs start vomiting before the diarrhea appears.
- Profuse, bloody diarrhea: The stool may look like raspberry jam, with a thick, dark red, or almost black appearance. It also often has a distinct, metallic odor due to the presence of blood.
- Lethargy and weakness: Rapid fluid loss from vomiting and diarrhea can lead to lethargy in dogs, a reluctance to move, or even the dog collapsing.
- Dehydration: The gums of dogs suffering from HGE might be tacky, they may have a dry nose or sunken eyes, and their skin, if pinched gently away from their body, may stay tented instead of springing back to normal. All these signs point to dehydration in dogs.
- Loss of appetite: Most dogs with HGE won’t want to eat or drink.
- Abdominal pain: Dogs with painful bellies may be whining, trembling, or assuming a “downward dog” or “prayer pose” posture. Plus, they may have a tense or guarded abdomen.
Potential complications of HGE
The biggest danger with HGE is the severe fluid loss. Profuse diarrhea with or without vomiting can lead to a specific kind of shock known as hypovolemic shock. It occurs when a dog is significantly dehydrated and therefore has a lower-than-normal circulating blood volume. (Fluid makes up a significant portion of blood, so less fluid equals less blood available to circulate through the body.)
To give you an idea of how quickly things can take a turn for the worse in some dogs with HGE, hypovolemic shock and death can occur within 24 hours in the most severe cases.
Disseminated intravascular coagulation (DIC) is another rare but potentially fatal complication that can develop in some dogs with HGE. In dogs suffering from DIC, the body’s normal clotting process becomes overactive, causing tiny clots to form throughout the bloodstream.
Over time, this uses up clotting factors and platelets, leading to uncontrolled bleeding and organ damage. DIC is a life-threatening emergency that requires intensive care and can be fatal even with aggressive treatment.
If your dog might have HGE, go to the vet immediately
The moral of the story is that if your dog ever develops sudden bloody diarrhea plus vomiting or lethargy, it isn’t the time to take a “wait and see” approach. Do not try to treat HGE at home, as doing so could risk your dog’s life.
Early veterinary attention can make all the difference. It decreases the risk of these scary complications and ensures the best possible outcome for you and your four-legged family member. Noticing dog diarrhea with blood can be scary, so don’t hesitate to call your vet or make an emergency vet visit.
Which dogs tend to get HGE?
Hemorrhagic gastroenteritis can strike any dog, but it most commonly affects small to medium-sized breeds, especially:
- Miniature Schnauzers
- Toy Poodles
- Yorkshire Terriers
- Dachshunds
- Maltese
While it can appear at any age, middle-aged dogs seem to be at slightly higher risk.
What causes HGE in dogs?
There isn’t one clearly defined cause of hemorrhagic gastroenteritis in dogs. But there are some contributing factors. This is part of why the new name for HGE, acute hemorrhagic diarrhea syndrome, includes the word “syndrome.” (A syndrome is a collection of clinical signs that tend to occur together and characterize a particular condition, but without necessarily having one clearly identified cause.)
Stress or dietary factors
Stress, sudden dietary changes, dietary indiscretion, or recent boarding and grooming visits sometimes precede an episode, suggesting that environmental or emotional stress may play a role in AHDS in dogs.
The bacterium Clostridium perfringens
Researchers have also found a connection between the bacterium Clostridium perfringens and HGE. Clostridium perfringens can be part of the normal gut microbiome and cause no harm. However, in some situations, the balance of gut bacteria can shift, allowing the clostridium bacteria to multiply excessively.
Some strains of clostridium produce a toxin known as netF, which damages the lining of the intestines. This damage causes the intestinal wall to become “leaky,” leading to the sudden, bloody diarrhea and dehydration that are hallmarks of HGE. There isn’t a link between Clostridium perfringens or the netF toxin in every case of HGE. But growing evidence suggests that this bacterium, or perhaps a dog’s sensitivity to it, might play a role in many cases.
NOTE: Although there may be a link between HGE and clostridium bacteria, HGE in dogs is not contagious.
How is HGE in dogs diagnosed?
There is no single, definitive test for HGE. Instead, diagnosing HGE involves evaluating a dog’s symptoms, performing a thorough physical examination, and running several useful diagnostic tests. Because the disease can progress very quickly, your veterinarian may begin supportive care while working to confirm the diagnosis.
Physical exam
Your veterinarian will start with a detailed physical exam. As part of the evaluation, he or she will check for signs of dehydration, such as dry or tacky gums, a rapid heart rate, or a weak pulse. Dogs with HGE often appear weak, depressed, and may have abdominal discomfort, so the vet will note those signs, too.
Blood tests
One simple and cost-effective blood test for dogs, PCV/TS (packed cell volume/total solids), plays a crucial role in diagnosing many cases of HGE.
The packed cell volume is the percentage of red blood cells in the blood. In healthy dogs, a normal PCV typically ranges from 35% to 55%. But in dogs with HGE, the PCV is often higher than 60%. At the same time, the total solids should remain normal or may even be low.
This combination of a high PCV (hemoconcentration) with normal or low total protein is a classic finding that supports a diagnosis of HGE.
The vet may also recommend a complete blood count (CBC) and biochemistry profile. These more comprehensive blood tests can help assess overall organ function, detect inflammation or infection, and identify imbalances in electrolytes that can result from severe dehydration.
Fecal testing
The veterinarian will use fecal tests for dogs to rule out intestinal parasites such as hookworms, whipworms, or giardia, which can cause similar symptoms to HGE. In some cases, fecal PCR testing may be performed to detect bacterial infections like Clostridium perfringens. However, this testing takes several days to complete, so it can’t inform immediate treatment decisions.
Additional diagnostic tests
In certain cases, additional testing may include:
- Coagulation tests: If there is concern about blood-clotting disorders, such as disseminated intravascular coagulation (DIC), the vet may run coagulation tests.
- Abdominal imaging (X-rays or ultrasound): Imaging can help rule out other potential causes of vomiting and bloody diarrhea, such as pancreatitis in dogs or an intestinal obstruction.
What is the treatment for HGE in dogs?
Once the vet diagnoses the dog with HGE (and during the diagnostic process), the treatment focuses on stabilization and aggressive rehydration. In this condition, swift, supportive treatment can mean the difference between crisis and recovery.
Fluid therapy
The most important part of treatment for HGE is rapid fluid therapy to replace what the dog lost through vomiting and diarrhea. Most dogs require hospitalization for IV (intravenous) fluid therapy, which helps correct dehydration and restore normal blood volume.
Additional medications
To support the dog as he or she recovers, the vet may administer:
- Anti-nausea medications: Many dogs with HGE benefit from anti-nausea medications like Cerenia for dogs.
- Gastroprotectants: The vet may recommend antacids like omeprazole for dogs or other similar medications to allow the gut lining to heal.
- Antibiotics: For more severe cases, the vet may give the dog antibiotics. However, they aren’t warranted in all cases.
- Probiotics: Probiotics for dogs can help support the GI tract and restore normal bacterial populations.
Can you treat HGE in dogs at home?
There is no way to treat HGE at home, and trying to do so can put your dog in grave danger. If you suspect your dog has HGE, you need to bring your dog to your vet or the emergency clinic immediately for IV fluids and other treatments.
How long does HGE in dogs last?
Most dogs begin to show improvement within 24 to 48 hours, and many can return home after a short hospital stay. But they should be fed a bland diet for dogs for several days before gradually returning to their normal food.
What is the prognosis for dogs with HGE?
Luckily, the overall prognosis for dogs with HGE is excellent with prompt and aggressive care. One retrospective study published in the Journal of Veterinary Internal Medicine looked at 237 dogs hospitalized with suspected HGE/AHDS. In it, the survival-to-discharge rate was 96%. However, with delayed or insufficient treatment, the mortality risk rises sharply.
That said, there are risks and complications that can worsen the outcome. These include:
- Development of disseminated intravascular coagulation (DIC)
- Severely low blood protein levels (hypoproteinemia)
- Sepsis (extreme and damaging response of the body to an infection)
- Hypovolemic shock that is unresponsive to fluid therapy
Because of those risks, early recognition and aggressive treatment are critical to ensure your beloved canine companion has the best shot at a quick and complete recovery.
Does HGE reoccur in dogs?
Recurrence of HGE is relatively uncommon, but it does happen. Estimates suggest that 10–15% of dogs may have repeated episodes of HGE/AHDS.
HGE can have a happy ending
Hemorrhagic gastroenteritis (HGE) is a condition that strikes suddenly and looks terrifying. But as we’ve seen, it’s also one that carries an excellent prognosis when treated promptly. My patient from the beginning is a perfect example—what began as a frantic emergency turned into a full recovery within days.
When she arrived, she was so dehydrated that she was showing signs of hypovolemic shock. But within hours of starting IV fluids, her energy began to return, and her tail even started to wag a bit when we opened her crate for her treatments. By the next afternoon, she was back in her owner’s loving arms.
It never ceases to amaze me how quickly my HGE patients can turn around once their circulation and hydration are restored!
I hope my patient’s story provides some reassurance. Remember, even when symptoms seem dire, quick action and prompt veterinary care can make all the difference. With early treatment and attentive follow-up, most dogs with HGE go on to live happy, healthy lives—leaving their bout of illness firmly in the past.
Has your dog ever had HGE?
Please share below.
