The primary objective of this research was to examine the potential impact of normal lairage practices on Salmonella, Campylobacter and E. coli antimicrobial resistance patterns in swine following evisceration in an abattoir environment. Fecal samples were collected upon arrival at the abattoir and later from the cecum within cohort groups. Also non-cohort pig and environmental samples were collected from the abattoir for comparison purposes. Isolates of Salmonella, Campylobacter, and E. coli tested for resistance to a panel of antimicrobials as well as characterized by serotype, phenotype and genetic patterns as appropriate. The results indicate a wide variety of antimicrobial resistance and other patterns that were not consistent between arrival and post slaughter samples. The conclusion is that normal lairage practices do impact bacterial populations in the gut in a manner which alters their antimicrobial resistance profiles. Thus resulting antimicrobial resistance patterns from samples collected post slaughter are not useful measures for monitoring on-farm resistance since they are even farther removed from the source then arrival samples. These results will aid the swine industry and inform research and regulatory communities as they seek to develop and enhance surveillance systems which reflect the impact of on-farm antimicrobial use.