The Effect of Probiotics Supplementation on the Gut Microbiome of Healthy Dogs Assessed Using Metagenomic Sequencing: A Randomized Control Trial

Abstract

Abstract Objectives Dogs share similar gut microbiome (GM) with humans, making them a great model for investigating the effects of probiotics (PR) on GM and health. This randomized control trial examined changes in MB and health outcomes in household dogs after PR supplementation. Methods All dogs recruited were fed human grade cooked food ≥ 1 mo, not fed any cultured food, PR, prebiotics, or on antibiotics ≥ 3 mo, and absent of major diseases. Dogs were randomized to receive a daily dose of PR (20 billion CFU of L. reuteri, P. acidilactici, E. faecium, L. acidophilus, B. animalis, L. fermentum, L. rhamnosus) or placebo (PL) for 4 weeks. Owners completed a health survey and collected stool samples at baseline and 4 weeks after the intervention in both groups. Additional stool samples were collected 2 weeks after stopping the PR in the PR group. GM profiling was performed with metagenomic sequencing. Results Twenty three dogs in the PR and 19 dogs in the PL group completed the trial (5.6 ± 3.0 y, 69% male). PR had no effect on α-diversity. As compared to baseline, changes in β-diversity at the species level in 4.3% of GM were significantly affected by PR at week 4 (P < 0.001) but not at week 6. A significant increase (adj P < 0.01) for ≥ 2-fold in abundance was observed at week 4 as compared to baseline for 41 bacterial taxa, 29 (71%) of which belong in the Lactobacillus genus. The abundance of E. coli also decreased at week 4 in the PR group (2.8 folds, adj P < 0.01). The abundance of these taxa returned to baseline at week 6. Such changes in diversity or abundance were not observed with PL. Dogs fed PR tended to be at a lower risk of diarrhea during the trial (0% vs 16%, P = 0.08). No change in other health outcomes was observed. Conclusions Oral PR supplementation has a small but significant effect on GM in healthy dogs. Findings warrant further investigation with longer duration in populations at a higher risk of gastrointestinal diseases. Funding Sources NomNomNow Inc.