STUDY:
GENE EXPRESSION AND DIET IN DOGS. 
Raw vs kibble diets

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.

 

Key findings:

• 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.