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What is causing acute haemorrhagic diarrhoea syndrome in dogs?
  1. Magdalena Dunowska
  1. LW(vet), PhD, IVABS, Tennent Drive, Massey University, New Zealand 4442, e-mail:

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IDIOPATHIC acute haemorrhagic diarrhoea syndrome (AHDS) in dogs is characterised by acute onset of haemorrhagic diarrhoea, which is commonly, but not always, preceded by acute onset vomiting. Other clinical and laboratory findings include lethargy, tachycardia, hypothermia, increased haematocrit values and stress leukogram with neutrophilic left shift (Mortier and others 2015). All these likely reflect hypovolaemia and decreased perfusion of all internal organs, as they are quickly corrected with appropriate fluid therapy (Mortier and others 2015). The syndrome appears to be more common in winter months and affects predominantly young to mid-age, small breed dogs. The disease was originally referred to as ‘haemorrhagic gastroenteritis’, but it has been recently shown that histopathological changes are present exclusively in the intestines of affected dogs, and not in the stomach (Unterer and others 2014).

Since the causative agent(s) involved is not known, the diagnosis of AHDS is made based on exclusion of other causes of acute diarrhoea in dogs such as neoplasia, pancreatitis, an intestinal foreign body, infection with canine parvovirus type 2 (CPV-2) or enteropathogenic bacteria (eg, Salmonella, Yersinia or Campylobacter species), severe parasite burden, drug-induced damage to the intestinal lining (eg, due to non-steroidal anti-inflammatory drugs) among others.

Despite severe clinical presentation, the affected dogs respond well to therapy with marked improvement in clinical appearance within the first 48 hours of supportive treatment (Mortier and others 2015). Antibiotics are not recommended for routine treatment of AHDS, as affected dogs are typically not septic (Unterer and others 2015) and the use of antibiotics does not seem to influence the outcome of disease (Unterer and others 2011, Mortier and others 2015).

Are clostridia involved?

The aetiology of the syndrome has baffled researchers and veterinarians. Results of some studies suggested an apparent association between overgrowth of Clostridium species and AHDS (Unterer and others 2014, …

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