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.

Lactobacilli have played an important role in the gut health of pets. The aim of this research was to study the effects of isolated Lactobacilli (named L11) on the immune, nutrient metabolism, and gut health of cats. Twelve healthy adult cats were randomly assigned into two groups, the control group (CONTROL, n = 6, without any probiotics product) and the treatment group (probiotics, n = 6, L11 10⁹ CFU/kg feed), while using the same dry diet. On day 28, blood and fecal samples were collected, and the blood biochemical indices, fecal microbiota, short-chain fatty acids (SCFAs), immunological parameters, and odorous substances were separately tested. The triglyceride of the blood was decreased after using L11 (p < 0.05), which could probably alleviate the occurrence of cat obesity to some extent. The sIgA of the feces was increased by 30.1% (p < 0.05), which could enhance the cat’s immunity. The abundance of Bifidobacteria was increased after using L11 (p < 0.05), and the indole and 3-methylindole of the feces were both reduced compared with the control group; 3-methylindole was especially reduced by 67.3% (p < 0.05), which showed that L11 could also improve the intestinal state of cats. Therefore, this research shows that L11 could be a good choice to improve the gut health and immune functions of cats, and it is probably related to the lipid mechanism of cats.

Objectives: The purpose of this study was to find the potential mechanism of two Lactobacillus (Lactobacillus plantarum L11 and Lactobacillus reuteri LR) on ameliorating obesity, including lipid metabolism and gut microbiota. The two isolates have been studied to have good characterization in vitro, but in vivo studies in modulating lipid metabolism and gut microbiota were not studied. Methods: In this study, mice with HFD supplemented with L11 or LR exhibited slower obesity progression, including reduced weight gain, abdominal fat accumulation, liver damage, inflammation, and adipose lesions. Results: Total cholesterol (TC) and triglycerides (TG) in the serum were significantly reduced (p < 0.01). The inflammatory marker interleukin-6 (IL-6) notably decreased (p < 0.05). Both Lactobacillus strains altered the gut microbiota composition, increasing the relative abundance of Alistipes and Lactobacillus, while L11 also raised Lachnospiraceae abundance. Results of the Western blot analysis showed that L11 and LR influenced the PPAR and AMPK pathways. Conclusions: L11 and LR can effectively reduce obesity by modulating gut microbiota and activating the PPAR–AMPK pathway, leading to decreased liver injury and systemic inflammation in mice fed with an HFD. In the future, the two probiotics may provide a new way for clinically ameliorating obesity on human beings.

Probiotics have been used in functional foods and dietary supplements, and in recent years, they have become more widely used in pets. In our previous experiment, Lactobacillus plantarum L-27-2 and Pediococcus lactis L-14-1 were isolated from cat feces and proved to have positive effects on lipid metabolism in mice. To further discuss their possible effects in cats, a total of 12 healthy cats (British Shorthair) were randomly divided into two groups. One group was fed Pediococcus lactis L-14-1 (1 × 10⁹ CFU/kg/d, n = 6), and the other group was fed Lactobacillus plantarum L-27-2 (1 × 10⁹ CFU/kg/d, n = 6), and the experiment was conducted for 28 days. Blood and feces were collected on days 0 and 28 separately. ELISA was used to detect blood biochemical indexes in cats. The results showed that L-27-2 and L-14-1 could reduce the content of TG (triglyceride, p < 0.05) and LDL-C (low-density lipoprotein cholesterol, p < 0.01) in the blood, increase the content of HDL-C (high-density lipoprotein, p < 0.01), and L-27-2 could significantly reduce the content of IL-6 (p < 0.01). The diversity of feces microbiota was also tested. On the phylum level, there was no significance in the phylum level of Firmicutes and Bacteroidetes (p > 0.05), but on the genus level, in the L-14-1 group, the abundance of Lantiplantibacillus and Cetobacterium was increased (p < 0.05), and the abundance of Ruminococcus, Olsenella, and Labanicoccus was decreased (p < 0.05), while in the L-27-2 group, the abundance of Libanicoccus was also decreased in L-14-1 (p < 0.05). Above all, L-27-2 and L-14-1 can be considered potential probiotics to improve cat gut health and lipid metabolism.

Yogurt and postbiotics are both beneficial for intestinal health of pets. This study was conducted to investigate the effects of yogurt with postbiotics in cats. A total of 18 adult cats were randomly divided into three groups, CK group (Control n = 6, free feeding and drinking without any probiotic products), Y group (Yogurt, n = 6, 50 g/day), and YP group (Yogurt + 2% postbiotics, 50 g/day), with the same environment and diet. On the 21st day, blood and fecal samples were collected and tested for biochemical indices, immunological parameters, inflammatory factors, and fecal flora, respectively. The results showed that feeding postbiotic yogurt to cats significantly reduced the levels of total bilirubin (TBIL), total bile acids (TBA), triglycerides (TG), glucose (GLU), urea nitrogen (BUN), creatinine (CREA), tumor necrosis factor-alpha (TNF-α), and Interleukin-6 (IL-6) (p < 0.05), and significantly increased Immunoglobulin A (sIgA) (p < 0.05) compared to the CK group. The abundance of Bifidobacterium in YP group was elevated, the Shannon violin plots showed that the intestinal flora of the YP group was less dispersed. Notably Enterococcaceae and Enterococcus were significantly elevated in the Y group (p < 0.05) and Streptococcus salivarius subsp. thermophilus in the YP group (p < 0.05). Therefore, this study suggests that yogurt with postbiotic is a good choice for improving intestinal health and immune function in cats and possesses good research and application prospects.

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.