Obesity is a major issue in pets and nutritional strategies need to be developed, like promoting greater protein and fiber intake. This study aimed to evaluate the effects of dietary protein levels and prebiotic supplementation on the glucose metabolism and relationships between the gut, microbiota, metabolome, and phenotype of obese dogs. Six obese Beagle dogs received a diet containing 25.6% or 36.9% crude protein, with or without 1% short-chain fructo-oligosaccharide (scFOS) or oligofructose (OF), in a Latin-square study design. Fecal and blood samples were collected for metabolite analysis, untargeted metabolomics, and 16S rRNA amplicon sequencing. A multi-block analysis was performed to build a correlation network to identify relationships between fecal microbiota, metabolome, and phenotypic variables. Diets did not affect energy homeostasis, but scFOS supplementation modulated fecal microbiota composition and induced significant changes of the fecal metabolome. Bile acids and several amino acids were related to glucose homeostasis while specific bacteria gathered in metavariables had a high number of links with phenotypic and metabolomic parameters. It also suggested that fecal aminoadipate and hippurate act as potential markers of glucose homeostasis. This preliminary study provides new insights into the relationships between the gut microbiota, the metabolome, and several phenotypic markers involved in obesity and associated metabolic dysfunctions.

It is generally accepted that microbes play a critical role in maintaining gut barrier function, making them ideal to target in order to mitigate the effects of intestinal diseases such as inflammatory bowel disease with specialist supplementations such as probiotic or postbiotic preparations. In this study, specific strains of Lactobacillus helvictus both live and inactivated and Lactobacillus plantarum inactivated were fed to zebrafish at an inclusion level of 6 × 10⁶ cells/g in order to assess the effects on gut barrier function and protection. Taken together, our results indicate that dietary administration of pro- or postbiotics strengthens the gut barrier function and innate immunity of healthy zebrafish in a strain-specific and process-dependent way. With some differences in the response intensity, the three treatments led to increased intestinal villi length and proportion of IELs, reinforcement of the GC population and up-regulated expression of biomarkers of AMP production and tight junction zona-occludin 2a (zo-2a). In addition, LPPost had an impact on the adaptive immune response, and we hypothesized that it conferred the potential to drive Th17/ILC3 immunity, as suggested by its effect on the gene expression of il22, of different AMPs, and the expression of zo2a. Moreover, LPPost showed the potential to drive Th1/ILC1-like immunity, with a higher percentage of CD8⁺ cells and higher ifnγ gene expression. In summary, the use of inactivated Lactobacilli species in this study represented a promising strategy for improving barrier function and regulating the immune fate of the intestinal mucosa in a strain-specific way.

Different dog sizes are associated with variations in large intestinal physiology including gut microbiota, which plays a key role in animal health. This study aims to evaluate, using the CANIM-ARCOL (Canine Mucosal Artificial Colon), the relative importance of gut microbes versus physicochemical and nutritional parameters of the canine colonic environment in shaping microbiota structure and functions. CANIM-ARCOL was set up to reproduce nutrient availability, bile acid profiles, colonic pH, and transit time from small, medium, or large dogs according to in vivo data, while bioreactors were all inoculated with a fecal sample collected from medium size dogs (n = 2). Applying different dog size parameters resulted in a positive association between size and gas or SCFA production, as well as distinct microbiota profiles as revealed by 16S Metabarcoding. Comparisons with in vivo data from canine stools and previous in vitro results obtained when CANIM-ARCOL was inoculated with fecal samples from three dog sizes revealed that environmental colonic parameters were sufficient to drive microbiota functions. However, size-related fecal microbes were necessary to accurately reproduce in vitro the colonic ecosystem of small, medium, and large dogs. For the first time, this study provides mechanistic insights on which parameters from colonic ecosystem mainly drive canine microbiota in relation to dog size. The CANIM-ARCOL can be used as a relevant in vitro platform to unravel interactions between food or pharma compounds and canine colonic microbiota, under different dog size conditions. The potential of the model will be extended soon to diseased situations (e.g. chronic enteropathies or obesity).

Gut microbiota plays a central role in dog health, supporting nutritional and physiological processes. However, antibiotic treatment can disturb microbiota equilibrium, leading to a perturbated state, called dysbiosis. While probiotic and postbiotic strategies are increasingly studied, their use in dogs remains poorly documented, particularly in the context of antibiotic-induced dysbiosis. In this study, we provide novel insights by evaluating for the first time, the efficacy of two microbiota restoration strategies using a canine-specific in vitro gut model (Canine Mucosal Artificial Colon, CANIM-ARCOL): the probiotic live yeast Saccharomyces boulardii CNCM I-1079 and the postbiotic heat-inactivated Lactobacillus helveticus HA-122. Both were administered at in-field doses twice a day, during and after a 5-day antibiotic treatment (metronidazole/enrofloxacin), to assess their ability to enhance microbiota resistance and/or promote recovery in both lumen and mucus-associated microbiota. Our results demonstrated that within two days post-antibiotic treatment, both interventions significantly mitigated the bloom of Enterobacteriaceae (up to −75% relative abundance, P < 0.05), accelerated the recovery of total bacterial load (increase of ∼1.5 copies/ml), and promoted a faster restoration of bacterial diversity (Shannon index returning to baseline by day 14 vs day 16 in the control). Additionally, S. boulardii significantly reduced redox potential (+200 mV with antibiotic vs only +80 mV with yeast, P < 0.0001), while L. helveticus preserved short-chain fatty acid concentrations (>100 mM vs 80 mM under control conditions) and upregulated beneficial metabolic pathways (e.g. norspermidine biosynthesis). Moreover, both treatments reduced variability in microbiota profiles and enhanced functional resilience post-antibiotic exposure. These findings provide compelling evidence supporting the relevance of probiotic and postbiotic strategies in companion animal and highlight the potential of the CANIM-ARCOL model as an ethical and robust alternative to in vivo trials for preclinical evaluation of microbiota-targeted intervention in canine nutrition and health.