Effects of supplemental seaweed extract on antioxidant properties, loose stools, gut microbiota, and its metabolite composition in adult dogs.

The objective of this study was to investigate the impact of seaweed extract (SWE) on the antioxidant properties, gut microbiota composition, and loose stools in adult dogs. A total of 30 Golden Retrievers were divided into three treatment groups. The dietary treatments administered were as follows: (1) healthy control: healthy dogs fed a basal diet; (2) loose stools control (LC): dogs with loose stools fed a basal diet; and (3) dogs with loose stools fed a basal diet supplemented with 20 g/kg SWE (LS), evenly top-dressed on the feed. The feeding trial lasted 28 d. Hematological analysis indicated that all dogs were healthy. Dietary supplementation with 2% SWE improved the loose stools of dogs compared to the LC group (P < 0.05). Dogs in the LS group had higher serum antioxidase activities and lower serum malondialdehyde concentrations compared to the LC group (P < 0.05). Meanwhile, serum levels of immunoglobulin A (IgA), IgM, and interleukin-10 (IL-10) were higher in the LS group than in the LC group (P < 0.05). However, serum levels of inflammatory markers (IL-1β, C-reactive protein, and tumor necrosis factor-α) and intestinal barrier markers (d-lactate, lipopolysaccharide, intestinal fatty acid-binding protein, and diamine oxidase) were lower in the LS group than in the LC group (P < 0.05). Furthermore, SWE increased SCFA-producing gut microbiota (especially Bifidobacterium and Holdemanella) abundance and fecal propionate concentrations (P < 0.05), probably contributing to its antioxidant properties. Conclusively, supplementing 2% SWE to the diet of dogs can improve antioxidant properties and reduce loose stools in dogs, accompanied by the alterations in gut microbiota and its metabolite composition. Our findings provide data and theoretical support for the effects and applications of SWE in canine nutrition.