Hemorrhagic Gastroenteritis (Acute Hemorrhagic Diarrhea Syndrome) in Dogs

Acute hemorrhagic diarrhea syndrome (AHDS) is a dangerous disease that can be fatal without appropriate treatment. It was formerly referred to as hemorrhagic gastroenteritis, which is no longer widely used. It is a common condition that normally affects young to middle-aged small breed dogs. Diagnosis is complex as many other conditions present similarly to AHDS, but cases that receive early fluid therapy normally recover fully. Dogs with acute onset blood in the stools require emergency veterinary attention.

The severity of AHDS is linked to the speed of diagnosis, initiation of treatment, and less quantifiable factors such as the competence of the patient's immune system. Young dogs often have mild symptoms.  Dogs with poor immune systems or other underlying conditions may develop severe dehydration which is sometimes fatal.  Dogs that lose large amounts of blood from the condition are at risk of developing shock, a rapidly fatal condition if left untreated. 

Serious complications can develop in some cases.

The underlying disease process of AHDS is not completely understood. Several factors contribute to the syndrome including:

• Toxins produced by Clostridium perfringens
• Intestinal colonization by multiple other bacteria, viruses, and parasites
• Influence of diet on intestinal health
• Immune system health

Most dogs that develop AHDS have no history of environmental or dietary changes. Some dogs may have a history of intermittent gastrointestinal disease leading up to showing symptoms of AHDS.

The characteristic symptom is sudden onset of bloody diarrhea characterized by; red and watery stool with blood clots, frequent and small amounts with minimal fecal material. Sometimes black, tar-like stools are also noted.

There is no specific test for AHDS, investigation aims to rule out alternative diseases, such as parvovirus. Investigation of AHDS involves:

• Physical examination
• Bloodwork
• Testing of the stool or blood for infectious diseases
• Diagnostic imaging (Abdominal ultrasound, X rays)
• Endoscopy

Patients with AHDS require hospitalization with aggressive treatment in order to prevent life-threatening conditions such as shock. Treatment options can include:

• Fluid therapy
• Correction of electrolyte abnormalities
• Supportive feeding
• Probiotic treatment
• Anti-nausea medication
• Antibiotics
• Pain relief

During treatment, dogs require frequent blood work and evaluation to ensure that treatment is effective.

Prognosis is good and most dogs with AHDS recover if treated promptly. Different factors that influence prognosis include how quickly treatment is initiated, and protein levels in the blood during the initial investigation. Dogs with low protein levels and delayed treatment have a poorer prognosis.

Prevention of AHDS is not possible as the disease process is not fully understood. It usually occurs in otherwise healthy dogs and there is no obvious breed-related susceptibility. Clostridium perfringens is present worldwide and is found in many dogs that do not have AHDS.

AHDS is a common presentation in dogs.

Treatment options include:

• Fluid therapy
• Correction of electrolyte imbalance
• Supportive feeding
• Probiotic treatment
• Antiemetic medication
• Pain relief