Dendrogram of pulsed-field gel electrophoresis (PFGE) profiles from 50 Escherichia coli isolates from 25 pups originating from kennel A. A: Isolate origin. A-a, A-b, A-c, A-d, A-e, A-f, A-g, and A-h litters consisted of three (A-a-1 to A-a-3), three (A-b-1 to A-b-3), two (A-c-1 to A-c-2), three (A-d-1 to A-d-3), four (A-e-1 to A-e-4), five (A-f-1 to A-f-5), three (A-g-1 to A-g-3), and two pups (A-h-1 to A-h-2), respectively. Two isolates were obtained per pup.B: Resistance pattern. AMP, ampicillin; DHS, dihydrostreptomycin; GEN, gentamicin; KAN, kanamycin; OTC, oxytetracycline; CHL, chloramphenicol; SXT, trimethoprim-sulfamethoxazole; NAL, nalidixic acid. C: PFGE profile.