Effects of Postbiotic Administration on Canine Health: A Systematic Review and Meta-Analysis.

Postbiotics-defined in 2021 by the International Scientific Association of Probiotics and Prebiotics (ISAPP) as preparations of inactivated microorganisms and/or their components that confer health benefits to the host-are a promising tool in veterinary medicine. This systematic review and meta-analysis evaluated their types, mechanisms of action, and physiological effects in dogs. A literature search was conducted in PubMed, Scopus, and Web of Science up to 10 October 2024. Eligible studies included peer-reviewed trials in dogs or mechanistic studies on postbiotics; studies in other species or without peer review were excluded. Risk of bias was assessed, and random-effects meta-analyses were performed when appropriate. Of 157 records, 69 met the inclusion criteria, including 13 in vivo studies in dogs. Meta-analyses of selected outcomes showed no statistically significant differences between postbiotic and control groups. Evidence is limited by small sample sizes, strain heterogeneity, and varied study designs. Despite nonsignificant results, existing evidence from other species suggests that postbiotics improve the gut microbiota composition, modulate immune and inflammatory responses, reduce oxidative stress, and aid in the treatment of chronic conditions such as atopic dermatitis. Taken together with their potential role as an alternative to antimicrobial use, these findings highlight the need for further research in canine health to support the use of postbiotics in the treatment of common canine diseases, either as a standalone therapy or in combination with existing therapeutic options.