Dexamethasone (Dex), a synthetic glucocorticoid (GC), in feed has been shown to 
increase gut permeability via stress-mediated mechanisms, but the exact mode of 
action on gut barrier function is not fully understood. Stress has been reported 
to alter the profile and virulence of intestinal flora predisposing for 
opportunistic disease. This study aimed to evaluate the relationship between 
dietary Dex and recoverable intestinal microbial profile in broilers to better 
understand mode of action and refine future uses of the model. Three experiments 
were conducted that administered Dex-treated feed for one week in conjunction 
with the antibiotics BMD (bacitracin methylene disalicylate) or Baytril® 
(enrofloxacin) to evaluate if enteric microbial mechanisms were important in 
Dex-induced permeability. Serum fluorescein isothiocyanate-dextran (FITC-d) and 
bacterial translocation (BT) have been reported to increase after Dex treatment 
and were used to assess gut epithelial leakage. Shifts in bacterial profiles 
were also measured on selective agar. Combining Dex with BMD or Baytril resulted 
in increased (P < 0.05) serum FITC-d versus Dex-only. Additionally, Baytril did 
not reduce aerobic BT and bacterial profiles remained similar after Dex. These 
results suggest a minimal role of intestinal microbes in Dex-induced changes to 
intestinal barrier function.