This study aimed to investigate the role played by pets as reservoirs of Escherichia coli strains causing human urinary tract infections (UTIs) in household contacts. Among 119 patients with community-acquired E. coli UTIs, we recruited 19 patients who lived with a dog or a cat. Fecal swabs from the household pet(s) were screened by antimicrobial selective culture to detect E. coli displaying the resistance profile of the human strain causing UTI. Two dogs shed E. coli isolates indistinguishable from the UTI strain by pulsed-field gel electrophoresis. Ten months later, new feces from these dogs and their owners were screened selectively and quantitatively for the presence of the UTI strain, followed by core-genome phylogenetic analysis of all isolates. In one pair, the resistance phenotype of the UTI strain occurred more frequently in human (10⁸ CFU/g) than in canine feces (10⁴ CFU/g), and human fecal isolates were more similar (2–7 SNPs) to the UTI strain than canine isolates (83–86 SNPs). In the other pair, isolates genetically related to the UTI strain (23–40 SNPs) were only detected in canine feces (10⁵ CFU/g). These results show that dogs can be long-term carriers of E. coli strains causing UTIs in human household contacts.