Jinquan Wang

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.

Wle vanillin is widely used as a flavoring agent in food products, its potential as a non-antibiotic feed additive for broilers remains unexplored. This study primarily investigated the effects of dietary supplementation of vanillin on antioxidant activity, anti-inflammatory response, immune function, and gut microbiota composition in broilers. One-day-old male broilers were randomly assigned to five groups: a basal diet group, a positive control group (basal diet + 100 mg/kg chlortetracycline (CTC)), and three vanillin-supplemented groups (0.1%, 0.2%, or 0.4%) for 42 days. Results showed that vanillin improved antioxidant capacity, with elevated serum superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity and reduced malondialdehyde (MDA) levels. Broilers receiving vanillin supplementation showed lower levels of pro-inflammatory cytokines (interleukin-6 (IL-6), interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α)) and higher interleukin-10 (IL-10) expression compared with controls. Additionally, serum immunoglobulin A (IgA) and immunoglobulin M (IgM) levels were also greater in the vanillin group. It also enhanced intestinal health by increasing the duodenal villus height-to-crypt depth ratio, improving intestinal morphology, raising the Firmicutes-to-Bacteroidetes ratio, and promoting Lactobacillus proliferation compared with CTC. Notably, growth performance data were exploratory in nature; vanillin was associated with numerical improvements in average daily gain (ADG) and feed conversion (F/G) ratio. These preliminary findings suggest that vanillin requires further investigation as a potential feed additive.

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.

While vanillin is widely used as a flavoring agent in food products, its potential as a broiler feed additive remains unexplored. This study primarily examined the effects of dietary supplementation of vanillin on broilers' antioxidant activity, anti-inflammatory response, immune function, and gut microbiota composition. One-day-old male broilers were randomly assigned to five groups: a basal diet group, a positive control group (basal diet + 20% chlortetracycline (CTC) premix), and three vanillin-supplemented groups (0.1%, 0.2%, or 0.4%) for 42 days. Results showed that vanillin significantly enhanced average body weight (ABW) and average daily gain (ADG) while reducing the feed-to-gain ratio (F/G). It exerted potent anti-inflammatory effects by downregulating interleukin-6 (IL-6), interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α) while upregulating interleukin-10 (IL-10). Vanillin also improved antioxidant capacity, with elevated serum superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity and reduced malondialdehyde (MDA) levels. Additionally, vanillin significantly increased serum immunoglobulin A (IgA) and immunoglobulin M (IgM) levels in 42-day-old broilers. It also enhanced intestinal health by increasing the duodenal villus height-to-crypt depth ratio, improving intestinal morphology, raising the Firmicutes-to-Bacteroidetes ratio, and promoting Lactobacillus proliferation. Notably, the 0.1% vanillin group demonstrated the most pronounced benefits among all treatments.

Owing to their favorable stability and safety profile, postbiotics—defined as functional metabolites originating from probiotic microbes—have attracted growing interest in the field of companion animal health care. The present work sought to evaluate how postbiotics prepared from Lactiplantibacillus plantarum and Pediococcus lactis influence lipid metabolism, blood biochemistry, and the composition of fecal microbiota in felines. Eighteen clinically healthy adult cats were assigned at random to three equal-sized groups: a control treatment (n = 6, a basal diet), a L. plantarum postbiotic L-27-2 group (n = 6, a basal diet with 10⁹ CFU equivalent/kg/day), and a P. lactis L-14-1 postbiotic group (n = 6, a basal diet with 10⁹ CFU equivalent/kg/day). The supplementation lasted four weeks. Both postbiotics significantly lowered serum total cholesterol (TC) and triglycerides (TG) concentrations (p < 0.05), demonstrating a modulatory action on lipid metabolism in cats. The L-27-2 postbiotic selectively enriched beneficial taxa, notably Bifidobacterium (p < 0.05). Furthermore, fecal levels of malodorous compounds were significantly decreased by both treatments (p < 0.05). The results suggested both postbiotics have potential positive effects in cats. These findings are preliminary and hypothesis-generating.

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.

Approximately 10–24% of people suffer from a cat allergy. Fel d 1, the major allergen, triggers reactions in approximately 94% of sensitized individuals. Current therapeutic strategies for allergic diseases primarily involve medication or immunotherapy to alleviate symptoms, which are often burdened by low efficacy, high cost, and extended duration, posing significant challenges for patients. In contrast, IgY antibodies offer a promising alternative by reducing the level of allergens produced by cats. In this study, T-cell epitopes of Fel d 1 were predicted using ProPred/CTLpred, connected via a suitable linker (GGGGS), and expressed in E. coli. Immunization of mice and hens with recombinant cFel d 1 yielded high-titer specific antibodies (IgG: 1:301,500; IgY: 1:4,194,304). Cats administered anti-cFel d 1 IgY-enriched yolk powder (1–3% of diet) for four weeks exhibited a 30–71% reduction in salivary Fel d 1. These findings indicate that the allergen epitope-targeted IgY strategy effectively reduces allergen levels in cats, providing a promising basis for preventing and treating allergic conditions.

Probiotics have grown increasingly pivotal for the health of pets, particularly dogs and cats. Emerging research demonstrates that probiotics exert a significant positive impact on gut health, including alleviating intestinal inflammation, regulating gut microbiota balance, and relieving diarrhea symptoms for pets. Regarding nutrient metabolism, probiotics aid in prevention and management of obesity and associated metabolic diseases, primarily by enhancing nutrient digestibility and regulating energy utilization and fat metabolism. Furthermore, probiotics exhibit positive effects, including antiviral activity, immune regulation, and antioxidation. Specific probiotic strains exert their functions via mechanisms such as increasing immunoglobulin levels, suppressing the expression of inflammatory factors, and boosting antioxidant enzyme activity. The underlying mechanisms primarily involve regulating metabolites (e.g., short-chain fatty acids, SCFAs), strengthening the intestinal barrier function, modulating immune responses, and optimizing the gut microbial composition. While existing studies highlight the broad potential of probiotics in preventing and managing various chronic diseases in dogs and cats, their utility in addressing acute illnesses and severe organ damage remains limited. Future research should prioritize investigating species-specific mechanisms of actions and extend to exploring potential applications in the neurological health and behavior of pets.