Dogs can eat tuna, but only in small amounts and occasionally. Tuna is not toxic to dogs and is even included in some commercial dog foods. It provides benefits like protein, omega-3 fatty acids for heart and skin health, and various vitamins and minerals. However, tuna can have high levels of mercury, which can build up in a dog's system over time and cause serious health problems, including mercury poisoning. Therefore, tuna should only be offered rarely and in limited portions. Canned tuna packed in water without added salt, oil, or spices is safest. Tuna packed in brine or oil or with seasonings should be avoided, as salt and additives can harm dogs. Fresh tuna should be cooked plain and served without any oils or flavorings. Raw tuna is not recommended due to potential parasites and bacteria. Overall, tuna can be a healthy treat for dogs in moderation but should not be a regular part of their diet due to mercury risk and potential additives in canned tuna. Always monitor your dog for any adverse reactions when offering tuna for the first time and consult your vet for specific advice based on your dog's health.