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The identification of three Arizona ridgenose rattlesnakes (Crotalus willardi) with Salmonella arizonae-associated osteomyelitis led to a 5-yr prospective study of radiographic signs and Salmonella intestinal carriage rates in a 19-member colony of this rattlesnake species. Ventrodorsal radiographs were performed and cloacal swabs were cultured for Salmonella spp. annually. Ten snakes survived the 5-yr period, with six of them remaining free of bony lesions. Three snakes that had no bony lesions in 1995 developed radiographic signs of osteomyelitis during the study. Six snakes with bony lesions at the beginning of the study died or were euthanatized due to osteomyelitis during the study. The radiographic signs of osteomyelitis were progressive for five snakes that were serially radiographed. Only one snake with radiographic signs of osteomyelitis at the beginning of the study was still alive at the end of the study, and this animal's bony lesions were more extensive at the end. Thirty-nine intestinal S. arizonae isolates, representing 13 serotypes, were obtained from the 19 snakes. Salmonella arizonae serotype 56:Z4,Z23 was isolated only once from a cloacal culture, from a snake that had no radiographic bone lesions. Twelve extraintestinal Salmonella isolates, representing two serotypes, were isolated from six snakes. All extraintestinal isolates except one were of S. arizonae serotype 56:Z4,Z23, and all isolates from bone were of this serotype. One snake with characteristic bone lesions died, and Providencia rettgeri was cultured from each of the tissues cultured, whereas no Salmonella spp. were isolated from this snake. Salmonella arizonae serotype 56:Z4,Z23 [corrected] appears to have a tropism for bone and other extraintestinal sites in C. willardi and may cause a progressive, ultimately fatal disease in this species.