Background: To investigate the effects of probiotics and their postbiotics on mouse health, this study utilized healthy mice randomly assigned to a control group (CK, n = 6), a probiotic group (L, n = 6, oral gavage 200 μL Pediococcus lactis), and a postbiotic group (PL, n = 6, oral gavage 200 μL Pediococcus lactis postbiotic). Methods: Following 21 days of continuous intervention, changes in gut metabolic profiles, microbial community structure, tissue morphology, and tight junction protein expression were systematically analyzed using metabolomics, 16S rRNA sequencing, hematoxylin and eosin (HE) staining, and immunohistochemistry techniques. Results: The results revealed that screening for significantly altered endogenous metabolites identified core differences concentrated in metabolites related to intestinal barrier repair, anti-inflammation, and antioxidant activity (e.g., 3-indolepropionic acid, astaxanthin, hydroxybenzoic acid). 16S rRNA sequencing revealed that the overall community structure was relatively stable according to principal component analysis, although differences were detected in specific taxa. However, LEfSe analysis identified significantly enriched functional microbial groups at multiple taxonomic levels in the PL group: phylum: Actinomycetota; class: Coriobacteriia; order: Coriobacteriales, Erysipelotrichales; family: Erysipelotrichaceae, Eggerthellaceae; genus: norank_Erysipelotrichaceae, Intestinimonas. These results suggest that although the overall community structure remained relatively stable, specific taxa may have differed between groups. Hematoxylin and eosin staining revealed no pathological lesions in intestinal tissues from either group, with intact mucosal architecture. Immunohistochemistry demonstrated significantly elevated expression of intestinal tight junction proteins Claudin 1, MUC-2, Occludin, and ZO-1 in the PL group compared to the CK group (p < 0.001). Conclusions: In summary, this probiotic (Pediococcus lactis) and its postbiotic showed promising effects, which may be related to changes in specific microbiota taxa, intestinal metabolic profiles, and tight junction protein expression. Beyond maintaining gut microbiota and tissue homeostasis, it enhances intestinal barrier function, suppresses latent inflammation, and boosts antioxidant capacity. Postbiotics may exhibit superior efficacy compared to probiotics. This provides robust experimental evidence for its development and application in gut health products for healthy populations. However, these findings still require further validation in studies with longer intervention periods and in disease models.

With the development of the pet industry, public attention to pet food safety and nutritional health has been continuously increasing. Postbiotics were initially defined as inactivated microorganisms or microbial cellular components that confer health benefits to the host. Compared with probiotics, postbiotics possess superior safety and stability. They can effectively eliminate the potential risk of horizontal transfer of drug-resistant genes carried by live bacteria, and also feature better manufacturability and storage performance. At present, most research on postbiotics has focused on humans and large domestic animals, with relatively few applications in dogs and cats. This indicates that further research on postbiotics in canines and felines is still needed to better promote their practical application in promoting pet food health. This article provides a comprehensive review of the current research status of postbiotics, focusing on their potential benefits and mechanisms for pet health. It proposes that future studies should concentrate on in vivo experimental validation to clarify the safety, optimal dosage, and specific functions of postbiotics in companion animals. Such research will offer a scientific basis for the application of postbiotics in pet food formulations, ultimately promoting the health and welfare of pets.

Stem cell-based therapies, as regenerative and immunomodulatory strategies, show substantial potential in companion animals through tissue repair, functional recovery, and immune modulation. Despite advances in human stem cell research, veterinary clinical translation remains constrained by small sample sizes, short follow-up periods, and non-standardized cell dosing regimens and delivery protocols. The expanding repertoire of stem cell-based modalities and technologies—including mesenchymal stem cells, induced pluripotent stem cells, extracellular vesicles, and tissue engineering—provides promising avenues for clinical application. This review summarizes recent progress in stem cell-based therapies across multiple disease systems in dogs and cats, with particular attention to the molecular mechanisms underlying regenerative and immunomodulatory effects, cross-species translational strategies, current challenges, and combinatorial therapeutic approaches in companion animals. By examining mechanistic findings alongside preclinical and early clinical evidence, this review highlights the limitations of current knowledge and identifies research priorities for evaluating the safety and efficacy of stem cell-based therapies in dogs and cats.