This randomized, controlled study evaluated the effects of a nutraceutical diet on 69 dogs with behavioral disorders related to anxiety and chronic stress. Over 45 days, dogs fed the nutraceutical diet showed significant improvements in neuroendocrine markers: increased serotonin, dopamine, and endorphin levels, and reduced cortisol and noradrenaline levels—indicators of reduced stress. Additionally, there was a significant decrease in oxidative stress (measured via dROMs), suggesting antioxidant benefits. These findings highlight the potential of targeted nutritional support in managing stress related behavioral issues in dogs, offering a promising, non-pharmaceutical approach to enhancing emotional well-being and overall health.