GENE EXPRESSION AND DIET IN DOGS.
Raw vs kibble diets
Reference: Anderson, R.C, Armstrong, K.M. Young, W, Maclean, P, Thomas, DG 2018, “Effect of kibble and raw meat diets on peripheral blood mononuclear cell gene expression profile in dogs”, The Veterinary Journal, vol. 234, pp 7–10.
(Follow up to Bermingham et al., 2017 study)
Design: Randomised control trial
Sample: 16 adult, healthy dogs randomly selected from Massey University dog colony (one excluded), fed either a premium kibbled diet or a raw red meat diet for 9 weeks.
Intervention: Blood samples were collected at baseline (time 0), and after 3, 6 and 9 weeks to compare the peripheral blood mononuclear cell gene expression (PBMC) for each diet over time, and between diets at each time-point. Plasma immunoglobulin A (IgA) and IgG concentrations were measured as biomarkers of immune status.
The two diets were associated with differences in PBMC gene expression profiles, which corresponded with changes in plasma IgA concentrations.
The kibble diet caused more differences (75 pathways) compared to the meat diet (50 pathways).
After 3 weeks the kibble diet induced expression of pro-inflammatory cytokine genes, including CD40LG, interleukin (IL) 2 and IL1b, as well as other factors associated with increased immune responses, such as STAT6, TREM1, ITK, DOCK8 and MTD88.
In contrast, the meat diet inhibited expression of pro-inflammatory cytokines, including IL2, interferon g, CCL5 and IL15, and reduced the expression of immune-associated transmembrane receptors, such as FOXO1, CD40 and Toll-like receptor 4.
Plasma IgA concentrations were lower in the meat-fed dogs than the kibble-fed dogs after 3 weeks (P < 0.05), but not at 6 and 9 weeks (0.05 < P < 0.1). Diet did not affect plasma IgG concentrations.
Relevance: These results are consistent with the kibble diet having a pro-inflammatory effect and the meat diet having an anti-inflammatory effect. This is highlighted in the regulatory effects network, which shows numerous inflammatory processes activated in kibble-fed vs. meat-fed dogs at 3 weeks.