Effects of dietary supplementation with fish oil on in vivo production of inflammatory mediators in clinically normal dogs

Objective - To evaluate the effect of diets enriched with eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on in vivo production of interleukin (IL)-1, IL-6, tumor necrosis factor (TNF)-α, prostaglandin E₂ (PGE₂), and platelet-activating factor (PAF) in dogs. Animals - 15 young healthy dogs. Procedures - Dogs were randomly allocated to receive an isocaloric ration supplemented with sunflower oil (n = 5), fish oil (5), or fish oil plus vitamin E (5) for 12 weeks. At week 12, in vivo production of inflammatory mediators was evaluated in serum at multiple time points for 6 hours following stimulation with IV administration of lipopolysaccharide (LPS). Results - Serum activity or concentration (area under the curve) of IL-1, IL-6, and PGE₂ significantly increased after LPS injection in all groups but to a lesser extent in dogs receiving the fish oil diet, compared with results for dogs receiving the sunflower oil diet. Serum activity of TNF-α and PAF concentration also increased significantly after LPS injection in all groups but did not differ significantly among groups. Conclusions and Clinical Rellevance - A fish oil-enriched diet consisting of 1.75 g of EPA/kg of diet and 2.2 g of DHA/kg of diet (dry-matter basis) with an n-6:n-3 fatty acid ratio of 3.4:1 was associated with significant reductions in serum PGE concentrations and 10 and IL-6 activities. Results supported the use of EPA- and DHA-enriched diets as part of antiinflammatory treatments for dogs with chronic inflammatory diseases. Additional studies in affected dogs are warranted to further evaluate beneficial anti-inflammatory effects of EPA- and DHA-enriched diets.