Cognitive Improvement and Microbiota–Gut–Brain Axis Regulation by Lycium barbarum Polysaccharides and Glycopeptide in Laboratory-Kenneled Poodles

Kennel-housed dogs may experience chronic stress affecting cognition. This study compared the effects of Lycium barbarum polysaccharides (LBP) and glycopeptide (LbGP) on cognitive function in laboratory-kenneled poodles. Eighteen dogs were assigned to CON, LBP, or LbGP groups for 42 days. Cognitive tests were performed and serum, saliva, and feces were collected for subsequent analysis. Both supplements improved cognitive performance (e.g., increased the correct rate in the cylinder test by approximately 40.0%, both p < 0.001). LBP enriched beneficial bacteria (Faecalibacterium and Bacteroides, p < 0.05), reduced pathogens (Romboutsia and Terrisporobacter, p < 0.05), and predominantly influenced the indole pathway of tryptophan metabolism. LbGP specifically decreased Escherichia-Shigella and Corynebacterium, increased fecal SCFAs, and mainly targeted the 5-HT pathway. Both treatments regulated immune function (i.e., elevated IL-6 and IL-10) and antioxidant capacity; LBP significantly increased serum superoxide dismutase (SOD) levels by 6.8% (p < 0.01) and BDNF levels by 13.5% (p < 0.05), while LbGP elevated (p < 0.01) glutathione peroxidase (GSH-Px) levels by 20.9% and reduced salivary cortisol levels by 14.2% (p < 0.01). Overall, LBP and LbGP support canine cognition through distinct microbiota-related mechanisms, likely via the microbiota–gut–brain axis, suggesting their potential as functional feed additives for cognitive health.