Phenotypic features and phylogenetic background of extraintestinal hemolytic Escherichia coli responsible of mortality in puppies.

•Some E. coli pathogenic strains may cause enteric or extra-intestinal disease.•We examine high puppy mortality due to extra-intestinal pathogenic E. coli.•Bitch's milk could be the main source of ExPEC infection.•Isolated E. coli strains were assigned to phylogroup B2.•Strains were biofilm producers with ability to colonize and survive in the host.