Most dogs can eat lettuce without issue, but not all of them will. Talk to your vet before making any changes to your dog's diet; with his approval, add a spoonful of shredded or pureed lettuce to his regular food daily, to give his digestive system time to adjust. If he tolerates it well -- without vomiting or diarrhea -- gradually increase his servings and introduce other low-calorie leafy nutrients into his diet.
Benefits of Lettuce
Lettuce is just one type of leafy vegetable your dog can eat. Kale, spinach, chard and cabbage are others. You can feed any type of lettuce -- but the darker the leaf, the more nutrients your dog will get. For example, Romaine lettuce beats the iceberg variety tenfold in beta carotene, and has five times more vitamin C. Add flaxseed oil to make it more palatable, or puree it with additional greens, eggs and plain yogurt. If you plan to transition your dog to a raw diet, such as the BARF diet, consult your veterinarian to ensure a nutritionally balanced diet. Long-term health issues can occur without proper nutrition, especially in puppies.
Vegetables to Avoid
Not all vegetables are safe for dogs; Foods from the allium family, onions, garlic, chives and scallions, can be toxic. Mushrooms, avocado, chocolate, green tomatoes and uncooked potatoes are off the menu. Dried seaweed or nori is high in nutrients but also in iodine. Consult a vet before considering giving it. Too much plant fiber can induce gas; kale and cabbage are culprits.