Diet and age affect intestinal morphology and large bowel fermentative end-product concentrations in senior and young adult dogs

The objective of this study was to determine the effects of age and diet on intestinal morphology and large bowel fermentative end-product concentrations in healthy dogs. Small intestinal villus width, height, and area, and small intestinal and colonic crypt depth were measured. Large bowel digesta samples were analyzed for ammonia, SCFAs, and branched-chain fatty acids (BCFAs). SCFAs are considered to be beneficial fermentative end-products in the intestine because they exert trophic effects on intestinal cells. Twelve senior (age = 11.1 y ± 0.6 at baseline; 6 male, 6 female) and 12 young adult (age = 8 wk old at baseline; 6 male, 6 female) beagles were randomly assigned to 1 of 2 dietary treatments, an animal product-based diet (APB) and a plant product-based diet (PPB). Diets were fed for 12 mo. Jejunal (P = 0.03) and ileal (P = 0.02) villus height, and duodenal (P = 0.04) villus width were greater for dogs consuming the PPB diet. Young dogs had greater (P = 0.04) jejunal villus height, whereas senior dogs had greater (P < 0.001) colonic crypt depth. Ammonia concentrations decreased (P = 0.03) from proximal to distal colon and were higher in dogs consuming APB (P = 0.03). Age and treatment affected butyrate concentrations, with senior dogs (P = 0.04) and dogs consuming APB (P = 0.04) having higher concentrations. Both diet and age affected small and large intestinal morphology, and colonic fermentative end-product concentrations in dogs.