Acute haemorrhagic enteropathy

A hyperacute syndrome of unknown aetiology, characterized by sudden onset vomiting and bloody diarrhoea leading to rapid dehydration, haemoconcentration, and hypovolemia due to major loss of water and electrolytes that pass into the intestinal lumen.

The triggering cause is thought to be an increase in intestinal vascular and mucosal permeability associated with mucus hypersecretion, which causes red blood cells, plasma and fluids to enter the intestinal lumen. Increased permeability is caused by an abnormal local immune overreaction to bacteria or bacterial toxins (similar to endotoxic shock) or to a dietary component. It could even involve a type I hypersensitivity reaction (IgE- and mast cell-mediated allergic reaction). According to some authors, hyperactivity and stress can also contribute to the onset of the pathology.

Several studies have associated this pathology with the presence of bacteria of the genus Clostridium, which has led to speculation that this microorganism or its toxins could be the triggering cause. However, most experts believe that Clostridium is merely a complicating factor, since the inflammation and necrosis of the intestinal mucosa caused by this bacteria does not usually appear in cases of acute haemorrhagic enteropathy.

Symptoms

The disease can affect dogs of any age and breed, but it is more common in young adults (2 - 4 years) of toy or miniature breeds (Poodles, Miniature Schnauzers, Yorkshire Terriers, Pekingese).

The symptoms are usually peracute, appear in animals that are in good health, and are not associated with changes in habits (dietary, ingestion of foreign substances, etc.). The clinical picture is characterized by vomiting - sometimes bloody, haemorrhagic, generally foul-smelling and initially jelly-like diarrhoea, anorexia, depression, abdominal pain, and rarely fever

The animal may exhibit signs of shock, with a rapid, weak pulse and prolonged capillary refill time. It is important to note that there is no clinical evidence of dehydration (the skin fold test is usually normal) due to the peracute course of the disease.

Interpretation of laboratory tests

Diagnosis is differential, i.e., ruling out other pathologies that present with similar symptoms:

• Viral gastroenteritis, typical in puppies: parvovirus / coronavirus infection.
• Bacterial enteritis, particularly due to Salmonella.
• Leptospirosis - Acute pancreatitis
• Parasitosis: giardiasis, coccidiosis, trichuriasis, etc.
• Acute intestinal obstruction.
• Primary gastrointestinal diseases: ulcerative colitis - gastrointestinal ulceration (uncontrolled administration of NSAIDs for human use).
• Intoxication: lead, arsenic, thallium. Diagnosis will rely heavily on thorough history-taking and knowledge of the pathology associated with these toxins (neurological, renal, dermal signs, etc.).

The most notable features of haemorrhagic gastroenteritis are its peracute presentation in an otherwise healthy animal and haemoconcentration without apparent dehydration.

General Tests

• Complete blood count:
  Always shows marked haemoconcentration (Hct 60%-75%) due to acute, major fluid loss. A stress leukogram is usually observed, with leucocytosis, neutrophilia and lymphopaenia.
• Blood biochemistry:
  Hepatic transaminases may be elevated due to destruction of hepatocytes secondary to absorption of toxins and hepatic hypoxia. Urea may be moderately elevated (prerenal uraemia), usually associated with oliguria. Pancreatic enzymes are normal or only slightly elevated, which helps rule out pancreatitis. Total proteins are usually normal or decreased due to gastrointestinal losses. Ionic imbalance with hypokalaemia may occur.
• Stool parasites:
  Usually absent, although in some cases they can appear as an associated factor.

Specific tests (differential diagnosis)

• Clotting tests:
  Normal, except in advanced cases in which disseminated intravascular coagulation, usually sepsis-related, may occur. CT, aPTT, PT, and FDPs are elevated while the platelet count is decreased (consumptive thrombocytopaenia).
• Stool culture:
  Culture must be negative for pathogenic bacteria such as Salmonella, Campylobacter and Clostridium
• Parvovirus and coronavirus antigen tests:
  Negative.
• TLI (tripsine-like inmunorreactivity):
  Normal values (5-35 ng./ml). Values greater than 80 ng/ml are diagnostic of acute pancreatitis.

Bibliography

• GUILFORD, W.G.; CENTER, S.A.; STROMBECK,D.R. et al. (1996) : Strombeck´s Small Animal Gastroenterology. (3ª ed.) Saunders, pg. 433-435
• BUSH, B.M. (1999) : Interpretation of Laboratory Results for Small Animal Clinicians ( 6ª ed.) Blackwell Science Ltd., pg. 35-42
• MORGAN, R.V. (1997) : Handbook of Small Animal Practice ( 3ª ed.) Churchill Livingstone., pg. 360
• THE MERCK VETERINARY MANUAL (1998) 8º ed. pg. 302-303
• GREENE, C. E. (1998 ) : Clinical Microbiology and Infectious Diseases of the Dog and Cat. (2ª ed.) Saunders, pg. 608
• SIMPSON, K.W. (1999): Veterinary Clinics of North America: Small Animal Practice. vol. 29, nº 2, pg. 441-447
• GERMAN, A.J. (2001) : Journal of Veterinary Internal Medicine vol. 15 nº 1, pg.14-25
• LLOYD-EVANS, L.P. (1978) : Veterinary Record vol.103 nº11 pg. 247-248.
• WEESE, J. S. (2001) : Journal of Veterinary Internal Medicine vol. 15 nº 4, pg.374-378
• RALLIS, T.S. (1996) : Veterinary Clinical Pathology vol. 25 nº 2, pg. 65-68
• TRIBE, G.W. (2001) : Veterinary Record vol. 149 nº 10, pg. 310-311
• LOCHER, C. (2001) : American Journal Veterinary Research vol. 62, nº 2, pg. 211-216