Probiotic supplementation mitigates antibiotic-associated gut dysbiosis and improves clinical and physiological outcomes in adult Rex rabbits

Antibiotic-associated gut dysbiosis (AAD) is a life-threatening condition in rabbits due to severe disruption of cecal microbiota. This study evaluated the protective effects of probiotics against AAD induced by co-trimoxazole in adult Rex rabbits. Twenty-five rabbits were randomly allocated to five groups ( n = 5): Group 1 (control, saline), Group 2 (co-trimoxazole only), Group 3 ( Saccharomyces boulardii + antibiotic), Group 4 ( S. boulardii + Enterococcus faecium + antibiotic), and Group 5 ( S. boulardii + Pediococcus acidilactici + antibiotic). Antibiotic and probiotics were co-administered for 14 days, followed by probiotics alone until day 28. Fecal microbiology, hematology, serum biochemistry, body weight, feed intake, fecal consistency, and histopathology were assessed. The group receiving only antibiotic showed severe dysbiosis according to culture-based findings, characterized by a depletion of Escherichia coli , overgrowth of Klebsiella spp. and spore-forming anaerobes, reduced counts of lactic acid bacteria, 34.5% body weight loss, and 100% mortality during the study period. By contrast, probiotic-treated groups exhibited significant changes in selected cultivable fecal microbial populations, including partial restoration of beneficial bacteria and suppression of opportunistic pathogens ( P < 0.05). Clinically, probiotics helped prevent diarrhea, maintain feed intake, and improve survival. Notably, the combination of S. boulardii and P. acidilactici resulted in a significant increase in body weight (21.4% by day 14 and 27.5% by day 28) and was associated with complete survival throughout the study period. The biochemical and hematological parameters remained within normal ranges in the multi-strain probiotic groups; in contrast, the antibiotic-only group showed elevated blood urea nitrogen, hypoproteinemia, reduced serum AST and ALT levels, and leukopenia. Histopathological findings confirmed severe intestinal, hepatic, and renal lesions in antibiotic-treated rabbits, whereas the apparent severity of these lesions was lower in probiotic-supplemented groups.In conclusion, multi-strain probiotics, particularly S. boulardii + P. acidilactici , were associated with attenuation of antibiotic-induced dysbiosis, improved clinical outcomes, and enhanced survival in rabbits receiving co‑trimoxazole. These findings suggest that probiotic supplementation may represent a promising approach for mitigating antibiotic-associated complications in rabbits.