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What is Acute Hemorrhagic Diarrhea Syndrome?

Acute hemorrhagic diarrhea syndrome (AHDS) in dogs, as noted above, is a new name for an old condition.  It is a condition which can affect virtually any age, gender or breed of dog, with small and toy breeds who are middle-aged being most often afflicted, seemingly to be more predisposed to it.  It is a condition which can be fatal if not treated in an appropriate and timely manner.

This syndrome is a newer name for an older condition in canines known as hemorrhagic gastroenteritis (HGE). The simple definition of acute hemorrhagic diarrhea syndrome (AHDS) in dogs is the inflammation of the stomach and intestine with bleeding.


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Symptoms of Acute Hemorrhagic Diarrhea Syndrome in Dogs

The symptoms are pretty much what one would expect from the name given to it:

  • Sudden onset of bloody diarrhea
  • Vomiting sometimes presents with the diarrhea
  • Anorexia
  • Decreased appetite
  • Lethargy
  • Abdominal pain
  • Hemoconcentration - Increased solids in the blood resembling  “raspberry jam”
  • Hypovolemic shock - Also called hemorrhagic shock, a life threatening condition that occurs when more than 20% of the body’s blood or fluid supplies are lost

Acute hemorrhagic diarrhea syndrome (AHDS) in dogs is an emergency situation.  Emergency veterinary medical care should be sought immediately.


There is only one type of acute hemorrhagic diarrhea syndrome in dogs and its etiology and exact pathogenesis are not clear, though research continues.   It does, however, have several levels of severity: 

  • Clinically insignificant AHDS
  • Mild AHDS
  • Moderate AHDS
  • Severe AHDS

These classifications are based on the symptoms, clinical signs and testing results.

This is what we know about AHDS:

  • It is known that AHDS is not contagious
  • Seems to be more common in young to middle aged canines
  • Seems more prevalent in the winter season
  • Diarrhea is quite watery and in increased quantities than normal
  • Diarrhea resembles pure blood sometimes
  • Urgency and straining sometimes accompanies AHDS

Acute hemorrhagic diarrhea syndrome seems predisposed to small and toy breeds like:

  • Yorkshire Terriers
  • Miniature Pinschers
  • Miniature Schnauzers  
  • Miniature French Poodles
  • Pekinese
  • Cavalier King Charles Spaniels
  • Shetland Sheepdog
  • Poodles

Causes of Acute Hemorrhagic Diarrhea Syndrome in Dogs

Though no specific cause for acute hemorrhagic diarrhea syndrome in dogs has been found, research into its causes does continue on an ongoing basis.  Here are some of the potential causes or contributing factors which have been found:

  • Clostridium perfringens, a species of bacteria which produce a toxin that can cause blood poisoning
  • Toxins (referenced above) which can ulcerate the lining of intestines and intestinal blood vessels, allowing fluids to leak through the intestinal walls, dehydrating the patient and causing sepsis (blood poisoning)
  • Stress and hyperactivity appear to be predisposing factors
  • Dietary indiscretions (ingestion of nonfood items or foods outside the normal dietary regimen of the dog)
  • Immune-mediated diseases
  • Pancreatitis
  • Allergic reactions (includes those inhaled as well as those ingested)
  • Intestinal parasites
  • Bacteria

Diagnosis of Acute Hemorrhagic Diarrhea Syndrome in Dogs

Diagnosis of acute hemorrhagic diarrhea syndrome in dogs can be challenging for your veterinary professional.  This is one of the many diseases or conditions in which your input can be important for obtaining the appropriate diagnosis quickly.  Your input will need to address the potential dietary regimen issue, activity levels of your pet, and any known allergies or previous allergic reactions.  Because the bloody diarrhea can be a symptom of a variety of conditions, your veterinary professional will need to eliminate as many of those other diseases and conditions as quickly as possible.  He will do a physical examination and will order blood testing which will likely include:

  • A complete blood count (CBC) to assess blood component values
  • Serum biochemical profile (CHEM) to assess liver function, kidney function and electrolytes
  • Urinalysis (UA) to assess kidney function and look for markers for inflammation and infection
  • Coagulation profile (PT/PTT) to ascertain if the canine’s blood is clotting appropriately

Ultimately, the diagnosis of AHDS will come based upon these criteria:

  • The sudden/acute onset of watery hemorrhagic diarrhea
  • Age of the afflicted canine - usually young or middle aged
  • Breed of the afflicted canine - generally small or toy breed
  • Percentage of red blood cells - usually elevated
  • Blood protein level - usually decreased

The diagnosis will include the level of severity which ranges from clinically insignificant to severe with treatment options being based, in part, upon that classification.

Treatment of Acute Hemorrhagic Diarrhea Syndrome in Dogs

Treatment options for AHDS will be dependent upon the level of severity with which the canine is afflicted.  Your vet will be primarily concerned with the immediate condition of your pet upon presentation in the clinic.  It is likely that your pet will be in some stage of dehydration and will require some emergency measures to stabilize him.  Fluids and most likely electrolytes will be administered intravenously.  It is imperative that your pet’s organs receive appropriate oxygenation and that can only happen if the fluid levels in his body are sufficient to allow those precious red blood cells to move through the vascular system to nourish all of those vital organs.  This is of utmost vital concern and will be addressed first.  Vitamins and minerals could also be added to the fluid regimen if the need is there.  Here are some other options which may be included in your pet’s treatment plan:

  • Analgesics - These medications will help ease the pain that your pet is enduring, making him more comfortable and able to relax
  • Antibiotics - The intestinal lining will need to be treated for bacterial infiltration into the bloodstream to prevent sepsis
  • Nutritional - This option will include dietary regimens which will restrict some of the types of foods consumed while your pet recuperates
  • Anti-nausea medications - Most canines who are afflicted with AHDS are also vomiting right along with the diarrhea; medications to ease the nausea will enable the canine to consume wholesome, healthy foods to regain strength

Recovery of Acute Hemorrhagic Diarrhea Syndrome in Dogs

This syndrome is considered to be relatively common in canines and it is treatable with success and good prognosis. The key is to be aware of the fact that, just as in humans, diarrhea and vomiting can dehydrate the body pretty quickly.  The canine body is generally smaller than most adult humans and dehydration will occur more rapidly than you might think.  Getting your canine to an emergency veterinary facility as quickly as possible when an acute hemorrhagic diarrhea syndrome episode strikes could mean the difference between the eventual return of your pet to your home or not.

Acute Hemorrhagic Diarrhea Syndrome Questions and Advice from Veterinary Professionals

Labrador Retriever
11 Years
Serious condition
0 found helpful
Serious condition

Has Symptoms

bloody, foul-smelling diarrhea

My 11 year old lab/Great Pyrenees mix developed AHDS DURING surgery today for some cyst removals, a tail amputation, and a dental cleaning. The diarrhea was described by the vet as almost constant, extremely foul-smelling , with bloody chunks present. I took her to an emergency clinic for overnight observation and support. She is currently receiving IV fluids and antibiotics. Would this possibly be a reaction to the anesthesia? She has had normal stools until this occurred. She had her annual checkup 3 days ago and bloodwork was good, although in general the vet and myself feel like she is declining. The vet said she felt like she looked 15 instead of 11. She has also had a persistent gagging cough for months, and at times her breath smells horrific. No idea if any of this is connected, but I keep feeling that we are missing something. She also has hypothyroidism to add to the mix. Would appreciate your thoughts!

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West Highland White Terrier
10 Years
Serious condition
0 found helpful
Serious condition

Has Symptoms

bloody nose

My westie contacted this disease and sadly died......he was given a blood transfusion but it started clotting and he took a heart attack .....I was told he had sepsis .....surely after all the blood tests they had been doing the vet should have recognized he had sepsis before giving him the blood transfusion ....I worry my wee dog died in pain and am totally heartbroken x

Dr. Michele King, DVM
Dr. Michele King, DVM
1611 Recommendations
I'm very sorry that Charlie had this happen to him, that is terribly sad. Without knowing more details about his lab work, it is hard for me to comment on it, but he sounds like he was in very critical condition, and blood transfusions need to be given when they are needed, regardless of sepsis or other conditions. I'm not sure that his sepsis would have changed that therapy, and he was most likely being treated with antibiotics at the time. I hope that gives you a little piece of mind, and again, I am very sorry for your loss.

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4 Years
Moderate condition
0 found helpful
Moderate condition

Can people food cause acute hemorrhagic diarrhea syndromeme. I don't have 160 characters worth of describing to put down.just a simple question can feeding me dog cause acute hemorrhagic diarrhea syndrome?

Dr. Callum Turner, DVM
Dr. Callum Turner, DVM
3320 Recommendations
Acute haemorrhagic diarrhoea syndrome is just another name for haemorrhagic gastroenteritis which is a severe bacterial infection of the gastrointestinal tract; the specific details of the onset of this disease is unknown but we know that Clostridium perfringens plays a large role. Whether feeding human food (something you shouldn’t do anyway) is a predisposing factor is up for debate. Regards Dr Callum Turner DVM

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2 Years
Mild condition
0 found helpful
Mild condition

Has Symptoms


Medication Used

No medications were prescribed

She consumed boric acid and she is alert but disorientated and not her normal self

Dr. Callum Turner, DVM
Dr. Callum Turner, DVM
3320 Recommendations

Dogs may be exposed to boric acid in a variety of ways; however small quantities are unlikely to cause many symptoms, inducing vomiting can help to bring up any remaining substance in the stomach but other regular poisoning treatments like activated charcoal are usually in effective. If the symptoms progress, it may be best to contact the Pet Poison Helpline and tell them the exact product name you are using as other ingredients may be toxic to dogs. Regards Dr Callum Turner DVM

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