Simple Summary: The impact of the gut microbiota on endurance performance remains unresolved. Here, we present an association between endurance performance and gut microbiota dysbiosis in sled dogs. We present evidence that normobiosis-associated bacteria prevent the outgrowth of dysbiosis-associated bacteria during the race.Abstract: Although our understanding of the role of the gut microbiota in different diseases is improving, our knowledge regarding how the gut microbiota affects functioning in healthy individuals is still limited. Here, we hypothesize that the gut microbiota could be associated with sled dog endurance-race performance. We investigated the gut microbiota in 166 fecal samples from 96 Alaskan Huskies, representing 16 teams participating in the 2016 Femund Race (400 km) in Norway, relating the microbiota composition to performance and metadata derived from questionnaires. For 16S rRNA gene sequencing-derived compositional data, we found a strong negative association between Enterobacteriaceae (dysbiosis-associated) and Clostridium hiranonis (normobiosis-associated). The teams with the best performances showed both the lowest levels of dysbiosis-associated bacteria prior to the race and the lowest change (decrease) in these bacteria after the race. Taken together, our results support the hypothesis that normobiosis-associated bacteria are involved in resilience mechanisms, potentially preventing growth of Enterobacteriaceae during the race.