Effects of an antioxidant-enriched kibble on serum oxidative stress and inflammatory biomarkers in healthy adult dogs and cats

This study investigated the effects of consuming antioxidant-enriched kibbles on serum oxidative stress and inflammatory biomarkers in healthy adult dogs and cats. A total of 30 adult dogs (13 male and 17 female, average age 4.46 ± 1.41 years, average body weight 9.83 ± 2.37 kg) and 30 adult cats (10 male and 20 female, average age 3.34 ± 3.19 years, average body weight 3.85 ± 1.07 kg) were used in two separate cross-over design studies, each consisting of two 28-d feeding periods with a washout period between. Protocols were approved by the facility's Institutional Animal Care and Use Committee (Summit Ridge Farm, Susquehanna, PA). Prior to the first feeding period, all animals were fed a commercial kibble diet for 14 days. During the feeding phases, animals were randomized to either a control diet (CON) or test diet (TEST), which included 95% CON and 5% antioxidant-enriched kibbles. The commercial kibble diet was provided during the washout phase between two feeding periods. Overnight-fasted blood samples were collected on days 0, 14, and 28 of each feeding period for oxidative stress and inflammatory biomarker analyses. All data were analyzed using the MIXED model procedures of SAS, with treatment, time, and their interactions considered as the fixed effects, whereas individual dog or cat as the random effect. Results from the dog study showed that dogs fed TEST tended (P < 0.10) to have lower serum concentrations of malonaldehyde (MDA) compared to those fed CON. However, no significant impact on inflammatory biomarkers was observed when dogs were fed TEST. In the cat study, cats fed TEST showed significantly lower (P < 0.05) serum MDA concentrations at both d 14 and d 28 compared to those fed CON. Additionally, cats fed TEST demonstrated elevated (P < 0.05) levels of serum FMS-like tyrosine 3 ligand, interferon gamma, interleukin-4 (IL-4), IL-6, IL-18, regulation on activation normal T-cell expressed and secreted (RANTES), and monocyte chemoattractant protein-1 (MCP-1), but had lower (P < 0.05) serum C-reactive protein (CRP) and Fas concentrations, compared to cats fed CON. In conclusion, incorporating additional antioxidant-enriched kibbles into the diets could reduce oxidative stress in both dogs and cats, and supports immune health, especially in cats.