Gastrointestinal (GI) afflictions are prevalent among the feline population, wherein the intricacies of the gut microbiome exert a profound influence on their overall health. Alterations within this microbial consortium can precipitate a cascade of physiological changes, notably in immune function and antioxidant capacity. This research investigated the impact of Bifidobacterium lactis (B. lactis) and Lactobacillus plantarum (L. plantarum) on cats’ GI health, exploring the effects of probiotic supplementation on the intestinal ecosystem using 16S rRNA gene sequencing. The findings demonstrated a significant improvement in gut barrier function by reducing plasma concentrations of D-lactate (D-LA) by 30.38% and diamine oxidase (DAO) by 22.68%, while increasing the population of beneficial bacteria such as Lactobacillus. There was a notable 25% increase in immunoglobulin A (IgA) levels, evidenced by increases of 19.13% in catalase (CAT), 23.94% in superoxide dismutase (SOD), and 21.81% in glutathione peroxidase (GSH-Px). Further analysis revealed positive correlations between Lactobacillus abundance and IgA, CAT, and total antioxidant capacity (T-AOC) levels. These correlations indicate that B. lactis and L. plantarum enhance feline immune and antioxidant functions by increasing the abundance of beneficial Lactobacillus in the GI tract. These findings provide a foundation for probiotic interventions aimed at enhancing health and disease resistance in feline populations.

Enterotoxigenic Escherichia coli (ETEC) infection is one of the most common bacterial causes of diarrhea in children and young farm animals. Medium-chain fatty acids (MCFAs) have been widely used for their antibacterial and immune functions. However, there is limited information regarding the role of MCFAs chelated with Zn in diarrhea induced by ETEC infection. Here, zinc laurate (ZnLa) was used to evaluate its protective effect in a mice diarrhea model induced by ETEC. A total of 45 ICR-weaned female mice were randomly assigned to marginal zinc deficiency (dZn), dZn, and ETEC infection groups (dZn+ETEC); ETEC infection was co-treated with a low, middle, or high dose of ZnLa (ZnLa LOW+ETEC, ZnLa MID+ETEC, and ZnLa HIGH+ETEC), respectively, to explore the effect and its mechanism of ZnLa on diarrhea and intestinal health of mice challenged with ETEC. To further compare the antibacterial efficiency of ZnLa and ZnSO₄ in mice with ETEC infection, a total of 36 ICR-weaned female mice were randomly divided into ZnLa, ZnLa+ETEC, ZnSO₄, and ZnSO₄ and ETEC infection groups (ZnSO₄+ETEC); moreover, the growth curve of ETEC also compared ZnLa and ZnSO₄ in vitro. Mice pretreated with ZnLa were effectively guarded against body weight losses and increases in diarrhea scores induced by ETEC. ZnLa pretreatment also prevented intestinal barrier damage and ion transport in mice challenged with ETEC, as evidenced by the fact that the intestinal villus height and the ratio of villus height and crypt depth, tight junction protein, and Na⁺ absorption were higher, whereas intestinal permeability and anion secretion were lower in mice pretreated with ZnLa. In addition, ZnLa conferred effective protection against ETEC-induced intestinal inflammatory responses, as the increases in protein and mRNAs of proinflammatory cytokines were prevented in serum and jejunum, which was likely associated with the TLR4/MYD88/NF-κB signaling pathway. The increase in ETEC shedding and virulence-related gene expression was prevented in mice with ZnLa pretreatment. Finally, the growth of ETEC and virulence-related gene expression were lower in the ZnLa group than in ZnSO₄ with an equal concentration of zinc. These findings suggest that ZnLa is a promising prevention strategy to remedy ETEC infection.

Immune deficiency is a prevalent issue among kittens, severely threatening their health and development by increasing susceptibility to infections and diseases. This study investigates the effects of dietary supplements containing lactoferrin and Lactobacillus plantarum (L. plantarum) on the immune function, intestinal health, and microbiota composition of kittens. The results demonstrate that these supplements significantly enhance immune responses, with immunoglobulin A (IgA) levels increasing by 14.9% and IgG levels by 14.2%. Additionally, there was a notable 28.7% increase in catalase activity, indicating a reduction in oxidative stress. Gastrointestinal (GI) health improved markedly, evidenced by increased populations of beneficial bacteria such as Lactobacillus, which rose from 4.13% to 79.03% over the study period. The DNC group also showed significant reductions in pro-inflammatory cytokines, including decreases of 13.94% in IL-2, 26.46% in TNF-α, and 19.45% in IFN-γ levels. Furthermore, improvements in physical conditions were observed, including enhanced coat condition and mental status. These findings underline the potential of lactoferrin and L. plantarum as effective dietary interventions to improve kitten health, thereby reducing dependency on antibiotics and mitigating associated risks. This research provides a scientific foundation for optimizing nutritional management practices to enhance the overall vitality of kittens during their critical growth phases.

This study evaluated the antibacterial efficacy of 700 feline-derived lactic acid bacteria (LAB) strains against enteropathogenic Escherichia coli (EPEC), a common cause of diarrhea in cats. Following comprehensive screening, strains ZY25 and ZY35 were identified as the most effective, with inhibition zones of ≥22 mm. These strains demonstrated strong tolerance against stress conditions, such as low pH, bile salts, and gastrointestinal fluids, alongside high hydrophobicity and auto-aggregation abilities. Safety evaluations confirmed the absence of hemolytic activity, virulence factors, and antibiotic resistance genes. The antibacterial activity of these strains is attributed to the production of organic acids, particularly lactic acid and acetic acid. These findings suggest that strains ZY25 and ZY35 have potential as natural and effective probiotic treatments for managing EPEC-induced diarrhea in cats, thus offering an alternative to conventional antibiotics.

Enteropathogenic Escherichia coli (EPEC) disrupts intestinal barrier integrity, induces inflammation, and alters gut microbial balance, leading to diarrhea and growth impairment. Probiotics are considered promising alternatives to antibiotics for managing enteric infections, yet the functional properties and underlying mechanisms of feline-derived strains remain unclear. This study evaluated the protective effects of Ligilactobacillus (L.) agilis ZY25 and L. salivarius ZY35, isolated from healthy cats, against EPEC-induced intestinal injury in C57BL/6 mice, with a focus on barrier function, immune modulation, and microbial homeostasis. In this 21-day experiment, 48 mice were assigned to six groups (n = 8/group): control, EPEC model (MOD), chlortetracycline treatment (CTC), probiotic treatment (PRO-T; post-infection only), probiotic pre-treatment (PRO-P; pre-infection only), and continuous probiotic supplementation (PRO; pre- and post-infection). EPEC challenge (0.2 mL; 1 × 10⁹ CFU/mL) was performed daily during experimental days 8–14. EPEC challenge resulted in weight loss (p < 0.05), increased (p < 0.05) diarrhea incidence, elevated (p < 0.05) serum D-lactate, diamine oxidase, and lipopolysaccharide levels, impaired intestinal morphology, immune imbalance, and microbial dysbiosis. Probiotic administration alleviated these alterations, as evidenced by restored intestinal morphology, reduced serum markers of barrier permeability (D-lactate, DAO, LPS), enhanced systemic immunoglobulins (IgA, IgG, IgM), a balanced cytokine profile (increased IL-4, IL-10; decreased TNF-α, IL-6, IL-1β, IFN-γ, CRP), and modulation of the gut microbiota (enrichment of beneficial taxa such as Lachnospiraceae_NK4A136_group and suppression of pro-inflammatory Desulfovibrio). The continuous supplementation regimen (PRO) produced the most consistent improvements among the three intervention strategies tested. These findings suggest that feline-derived probiotics mitigate EPEC-induced intestinal dysfunction, accompanied by improved barrier-related indices, immune rebalancing, and microbial stabilization, thereby providing proof-of-concept evidence for their further evaluation in feline gastrointestinal health.

Feline obesity is an increasingly prevalent health concern and is closely associated with metabolic disorders and intestinal dysbiosis. This study aimed to screen feline-derived lactic acid bacteria (LAB) for bile salt hydrolase activity, in vitro cholesterol-removal capacity, and selected probiotic-associated characteristics. Approximately 700 LAB isolates were obtained from fecal samples of healthy domestic cats and evaluated for bile salt hydrolase (BSH) activity, among which 105 isolates were identified as BSH-positive. Further screening was performed based on BSH activity, cholesterol-removal capacity, adhesion-related properties, antioxidant activity, gastrointestinal tolerance, antibacterial activity, organic acid production, hemolytic activity, and antibiotic susceptibility. Three candidate strains were ultimately selected and preliminarily identified by 16S rRNA gene sequencing as Enterococcus hirae C283, Ligilactobacillus animalis C289, and Enterococcus faecium C422. These strains exhibited BSH activity and preliminary in vitro cholesterol-removal phenotypes under the tested culture conditions, together with tolerance to simulated gastrointestinal conditions, antioxidant activity, antibacterial activity, and organic acid production. No hemolytic activity was detected; however, all three strains exhibited resistant or intermediate phenotypes to multiple antibiotics, highlighting the need for further genome-based safety assessment, particularly for the two Enterococcus strains. Overall, these findings identified feline-derived LAB candidates with BSH activity, preliminary in vitro cholesterol-removal phenotypes, and multiple probiotic-associated characteristics. However, these in vitro findings do not demonstrate regulation of host lipid metabolism or blood lipid levels. Comprehensive safety assessment, particularly for the Enterococcus strains, and in vivo validation are required before further application.