Acute Hemorrhagic Diarrhea Syndrome Research Articles

NetF-producing Clostridium perfringens and its associated diseases in dogs and foals.

The role of type A Clostridium perfringens in canine acute hemorrhagic diarrhea syndrome and foal necrotizing enteritis is poorly characterized. However, a highly significant association between the presence of novel toxigenic C. perfringens and these specific enteric diseases has been described. These novel toxigenic strains produce 3 novel putative toxins, which have been designated NetE, NetF, and NetG. Although not conclusively demonstrated, current evidence suggests that NetF is likely the major virulence factor in strains responsible for canine acute hemorrhagic diarrhea syndrome and foal necrotizing enteritis. NetF is a beta-pore-forming toxin that belongs to the same toxin superfamily as CPB and NetB toxins produced by C. perfringens. The netF gene is encoded on a conjugative plasmid that, in the case of netF, also carries another putative toxin gene, netE. In addition, these strains consistently also carry a cpe tcp-conjugative plasmid, and a proportion also carry a separate netG tcp-conjugative plasmid. The netF and netG genes form part of a locus with all the features of the pathogenicity loci of tcp-conjugative plasmids. The netF-positive isolates are clonal in origin and fall into 2 clades. Disease in dogs or foals can be associated with either clade. Thus, these are strains with unique virulence-associated characteristics associated with serious and sometimes fatal cases of important enteric diseases in 2 animal species.

Prevalence of Clostridium perfringens netE and netF toxin genes in the feces of dogs with acute hemorrhagic diarrhea syndrome

BackgroundRecently, novel pore‐forming toxin genes designated netE and netF were identified in a Clostridium perfringens type A strain isolated from a dog with acute hemorrhagic diarrhea.ObjectivesPore‐forming toxins could play an important role in the disease pattern of acute hemorrhagic diarrhea syndrome (AHDS) in dogs. Thus, we aimed to determine the prevalence of C. perfringens genes encoding for netE and netF in the feces of dogs with AHDS and to evaluate any association between selected clinical variables and the presence of these toxin genes.AnimalsIn total, 174 dogs were included in the study.MethodsFecal samples of all dogs were tested by real‐time polymerase chain reaction for netE and netF genes. Time to recovery, hospitalization time, and selected laboratory variables were compared between dogs with AHDS that were positive or negative for the toxin genes.ResultsA significant difference was found among the 3 groups in the prevalence of the pore‐forming toxin genes netE and netF: dogs with AHDS: 26 of 54 (48.1%); dogs with canine parvovirus (CPV) infection: 0 of 54 (0%); and healthy dogs: 8 of 66 (12.1%; P < .001). In dogs with AHDS, no significant difference was detected in any variables evaluated between netE‐positive and netF‐positive and netE‐negative and netF‐negative dogs.Conclusions and Clinical ImportanceThe prevalence of C. perfringens encoding for netE and netF is significantly higher in dogs with AHDS compared to control dogs. Further studies are warranted to evaluate whether these toxins are an inciting cause for AHDS in dogs.

Intestinal lesions in dogs with acute hemorrhagic diarrhea syndrome associated with netF-positive Clostridium perfringens type A.

Acute hemorrhagic diarrhea syndrome (AHDS), formerly named canine hemorrhagic gastroenteritis, is one of the most common causes of acute hemorrhagic diarrhea in dogs, and is characterized by acute onset of diarrhea, vomiting, and hemoconcentration. To date, histologic examinations have been limited to postmortem specimens of only a few dogs with AHDS. Thus, the aim of our study was to describe in detail the distribution, character, and grade of microscopic lesions, and to investigate the etiology of AHDS. Our study comprised 10 dogs with AHDS and 9 control dogs of various breeds, age, and sex. Endoscopic biopsies of the gastrointestinal tract were taken and examined histologically (H&E, Giemsa), immunohistochemically ( Clostridium spp., parvovirus), and bacteriologically. The main findings were acute necrotizing and neutrophilic enterocolitis (9 of 10) with histologic detection of clostridia-like, gram-positive bacteria on the necrotic mucosal surface (9 of 10). Clostridium perfringens isolated from the duodenum was identified as type A (5 of 5) by multiplex PCR (5 of 5). In addition, each of the 5 genotyped isolates encoded the pore-forming toxin netF. Clostridium spp. (not C. perfringens) were cultured from duodenal biopsies in 2 of 9 control dogs. These findings suggest that the pore-forming netF toxin is responsible for the necrotizing lesions in the intestines of a significant proportion of dogs with AHDS. Given that the stomach was not involved in the process, the term "acute hemorrhagic diarrhea syndrome" seems more appropriate than the frequently used term "hemorrhagic gastroenteritis."

Fecal markers of inflammation, protein loss, and microbial changes in dogs with the acute hemorrhagic diarrhea syndrome (AHDS).

Idiopathic acute hemorrhagic diarrhea syndrome (AHDS) is characterized by acute onset of bloody diarrhea, severe dehydration, and increased vascular and intestinal mucosal permeability. Markers of gastrointestinal inflammation, protein loss, and changes in the intestinal microbiota have not been studied extensively in dogs with AHDS. For 3 consecutive days, feces were collected from dogs with AHDS, and assayed for calprotectin and S100A12 (both markers of inflammation), α1 -proteinase inhibitor (a marker of gastrointestinal protein loss), and the presence of selected species of bacteria. Concentrations of all assayed markers were significantly greater than the institutional reference intervals at the time of presentation, and all decreased significantly by Day 3 of treatment. Abundances of selected bacterial groups (Ruminococcaceae, Faecalibacterium spp., Bifidobacterium spp., and Proteobacteria) at the time of diagnosis were consistent with an intestinal bacterial dysbiosis. No differences in the abundance of bacterial groups over time was seen, except for a mild but significant decrease in Ruminococcaceae at Day 3. These results suggest that canine AHDS is associated with a significant but transient gastrointestinal loss of protein and intestinal inflammation. The intestinal bacterial dysbiosis appears to outlast the protein loss and inflammation.

Role of canine circovirus in dogs with acute haemorrhagic diarrhoea

Canine circovirus (CanineCV) has been detected in some dogs with severe haemorrhagic diarrhoea, but its pathogenic role is unclear. This study evaluated a suspected association between the presence of CanineCV...

Acute haemorrhagic diarrhoea syndrome in dogs: 108 cases

No prospective studies including large numbers of dogs with acute haemorrhagic diarrhoea syndrome (AHDS) are published so far. The aim of this case–control study was to describe signalment, history, clinical...

Bacteria involved in acute haemorrhagic diarrhoea syndrome in dogs

DESPITE recent reports of antibiotic resistance in the UK being on the rise, antibiotics are still the number 1 choice of drugs for dogs presenting with acute diarrhoea in veterinary...

Prospective study of bacteraemia in acute haemorrhagic diarrhoea syndrome in dogs

In dogs with idiopathic acute haemorrhagic diarrhoea syndrome (AHDS), a serious loss of intestinal mucosal barrier integrity occurs. However, the incidence of bacterial translocation in dogs with idiopathic AHDS is...

Clostridium perfringens enterotoxin and Clostridium difficile toxin A/B do not play a role in acute haemorrhagic diarrhoea syndrome in dogs

Although an association between clostridial pathogens and canine idiopathic acute haemorrhagic diarrhoea syndrome (AHDS) has been described, the relevance of those bacteria and their toxins remains unclear. The aim of...

Endoscopically Visualized Lesions, Histologic Findings, and Bacterial Invasion in the Gastrointestinal Mucosa of Dogs with Acute Hemorrhagic Diarrhea Syndrome

BackgroundEtiology of hemorrhagic gastroenteritis (HGE) syndrome in dogs is unknown and histopathologic and microbial investigations have only been performed post mortem.ObjectiveTo identify characteristic intra vitam endoscopic and histologic mucosal lesions, as well as bacterial species, within the mucosa of dogs with HGE.AnimalsTen dogs diagnosed with HGE were included. Eleven dogs with gastroduodenoscopy and different intestinal diseases were used as controls for microbial changes. Dogs pretreated with antibiotics or diagnosed with any disease known to cause bloody diarrhea were excluded from the study.MethodsIn this prospective study, gastrointestinal biopsies were collected from 10 dogs with HGE. Endoscopic and histologic changes were assessed according to WSAVA guidelines. Biopsies from the stomach, duodenum, ileum, and colon were investigated by histology and by immunohistochemistry for the presence of Clostridium spp. and parvovirus. The first duodenal biopsy taken with a sterile forceps was submitted for bacterial culture.ResultsAcute mucosal lesions were only found in the intestines, not in the stomach. Clostridium spp., identified as Clostridium perfringens in 6/9 cases, were detected on the small intestinal mucosa in all dogs with HGE, either by culture or immunohistopathology. In the control group, C. perfringens could only be cultured in one of 11 dogs.Conclusions and Clinical ImportanceThe results of this study demonstrate an apparent association between C. perfringens and the occurrence of acute hemorrhagic diarrhea. The term “HGE,” which implies the involvement of the stomach, should be renamed as “acute hemorrhagic diarrhea syndrome.”