Upper extremity dog bite wounds comprise a large percentage of all mammalian bite wounds. The purpose of the study was to assess the bacteriology of patients presenting with such injuries to the emergency room that required consultation by a hand surgeon. The study also analyzed the effect of delayed intervention on growth of invasive pathogens, on the incidence of multiple pathogens, on treatment interventions, and on length of hospital stay. Objective data and subjective descriptions of the wound were collected on 32 patients who presented to Chicago area hospitals. The authors retrospectively analyzed the data and grouped the patients into two categories based on time of intervention: early or those treated within 48 hours, and delayed to include those treated after 48 hours. Incidence of bacterial growth and Pasteurella species growth in cultures was similar to that reported in the literature. Delayed patients had a significantly higher incidence of positive bacterial growth from wound cultures (100%) compared with nondelayed patients (54%). Delayed patients also had a higher incidence of treatment intervention (delayed group 86% surgical irrigation and debridement compared with 48% for the early group). There was a trend toward increased length of hospital stay (delayed group 4.6 days compared with 2.6 days), although this was not significant. The growth of multiple pathogens between the two groups was similar and not significant (delayed group 43% compared with 54% early group).