Effects of prebiotic inulin‐type fructans on blood metabolite and hormone concentrations and fecal microbiota and bile acids in overweight dogs

Obesity commonly affects both humans and companion animals, and is often associated with altered blood glucose and hormone responses. Many studies have shown the ability of dietary fibers or prebiotics to curb postprandial glycemic responses, but some have suggested that certain prebiotics, when consumed at an early meal, can even curb the responses after a second meal consumed hours later. This response has been coined the ‘second‐meal effect’. Although it is known that dietary prebiotics can elicit shifts in the fecal microbiota composition, little research has been performed in dogs using modern high‐throughput DNA‐sequencing. In this study, our objective was to evaluate the (1) second‐meal effect of a commercial prebiotic blend of inulin‐type fructans, and (2) effects of the prebiotic on fecal microbiota, metabolites, and bile acids (BA). We hypothesized that the prebiotic would elicit a second‐meal effect in response to an oral glucose challenge, beneficially shift fecal microbiota by increasing Bifidobacterium, Faecalibacterium, and Lachnospira and decreasing Fusobacterium and Desulfovibrio , and shifting the fecal BA composition. Nine overweight dogs (4.2 ± 0.7 yr, 12.7 ± 2.4 kg, 7.8 ± 1.4 BCS) were used in a replicated 3×3 Latin Square design to test a non‐prebiotic control (cellulose) against low‐ (0.5% of diet) and high‐dose (1.0% of diet) prebiotic treatments. The study included three 14‐d treatment periods separated by 14‐d washouts. All dogs were fed the same experimental diet formulated to meet all nutrient needs as defined by AAFCO, with treatments provided orally via gelatin capsules prior to each meal. Dogs were fed twice daily (8 am; 4 pm) to maintain BW. At the end of each period, fresh fecal samples were collected for microbiota, metabolite, and BA analysis. On d13 or d14 of each period, dogs were fed at 8 am as usual, then dosed with 1 g/kg BW of maltodextrin as a 50% solution in place of the 4 pm meal. Blood samples were collected at baseline and 10, 20, 30, 45, 60, 90, 120, and 180 min after dosing, and analyzed for glucose, insulin, and active glucagon‐like peptide‐1 (GLP‐1) concentrations. Baseline and postprandial incremental area under the curve (IAUC) data were analyzed statistically. The prebiotic tended to attenuate postprandial blood glucose response to the oral glucose challenge (p=0.089), but did not affect (p>0.10) baseline glucose or baseline and postprandial active GLP‐1. The prebiotic also tended to increase the relative abundance of fecal Erysipelotrichi (p=0.089), particularly in the genus Eubacterium (p=0.075), the order Turicibacterales (p=0.066), the family Veillonellaceae (p=0.051), and the genus Megamonas (p=0.054). Fecal lithocholic acid, a secondary BA, tended to decrease (p=0.083) in dogs fed the prebiotic. Our results indicate that inulin‐type prebiotics may elicit a second‐meal effect and serve as a modulator of the gut microbiota in overweight dogs. Support or Funding Information Funding provided by Beneo GmbH.