There are adhesive and invasive species among enteropathogenic bacteria for animals. Most frequently isolated adhesive bacteria are enterotoxigenic E. coli (ETEC). Salmonella, T. hyodysenteriae, M. paratuberculosis, Y. enterocolitica, Cl. perfringens and C. jejuni bacteria represent the most important invasive germs. The main clinical finding connected with bacterial enteritis is diarrhoea resp. dysentery. Evaluation of feces consistency, time of appearance and accompanying symptoms (e.g. fever, colic) allow a clinical suspective diagnosis, however a definitive diagnosis must be based on the demonstration of the causative agent. In addition to known cultural, microscopic, biochemical and serological diagnostic methods, the demonstration of virulence factors (enterotoxin formation, adhesive pili) plays an important role in diagnosis of enteropathogenic bacteria.