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

The role of type A in canine acute hemorrhagic diarrhea syndrome and foal necrotizing enteritis is poorly characterized. However, a highly significant association between the presence of novel toxigenic 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 . The gene is encoded on a conjugative plasmid that, in the case of , also carries another putative toxin gene, . In addition, these strains consistently also carry a -conjugative plasmid, and a proportion also carry a separate -conjugative plasmid. The and genes form part of a locus with all the features of the pathogenicity loci of -conjugative plasmids. The -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.