Food-producing animals are the primary reservoir of zoonotic pathogens, and the detection of extended spectrum beta-lactamase (ESBL) producers among Escherichia coli and Salmonella strains has increased in recent years. ESBLs are widely detected in various human medical institutions but they are not so frequently reported in the bacterial population circulating in animals. This could indicate that these enzymes are less prevalent in animals than in humans, but also that they have not been extensively sought. The increasing occurrence of ESBL producers in animals is highlighted and discussed in this review with respect to the circulation of these resistance traits also among human pathogens.