The efficiency of five natural antioxidants (curcumin, cranberry, pomegranate, grape seed extract (GSE) and açai berry) in reducing lipid oxidation in dog food was tested in comparison to the synthetic antioxidant butylated hydroxyanisole (BHA). Lipid oxidation was evaluated after 12 days of storage at 55C and thiobarbituric acid-reactive substances (TBARS) was measured as an indicator of lipid oxidation. In project one, the natural antioxidants were added at 0.2% and BHA at 0.02% of the food (DM basis) and samples were collected on day 12 and analyzed for TBARS. Compared with the control treatment, TBARS values were lower (p<0.01) for four antioxidant treatments (curcumin, cranberry, pomegranate and GSE) but not for the açai berry treatment (p<0.39). The four antioxidants showed similar efficacy at lowering lipid oxidation as BHA and therefore may have the potential to substitute BHA in dog food. In project two, we evaluated the effects of GSE and curcumin at two inclusion rates (0.1 and 0.2% of food DM) on TBARS and omega-3 fatty acid (FA) content over 12 days of storage at 55C. By day 12, our results showed no significant differences in TBARS values between the BHA and the 0.1% GSE treatment, however BHA was still more effective than the 0.1% GSE as the differences in fold increase in TBARS were lower for BHA (19.4%) than for the 0.1% GSE (75.5%) treatment. Omega-3 FA loss tended (P>0.11) to be greater at the lower inclusion rate which correlated with the increased TBARS values at the 0.1% when compared to the 0.2% inclusion rate. Curcumin and GSE were most effective at maintaining omega-3 FA content at the 0.2% inclusion rate and showed no significant differences from the BHA treatment. In conclusion, BHA in dog food can be effectively substituted by GSE, cranberry, curcumin and pomegranate at the inclusion rate of 0.2% of food DM.