Why
Romaine, iceberg and arugula are not toxic. Lettuce is mostly water with some fiber and beta-carotene; iceberg has the least nutrition.
How to serve lettuce
- Wash well and chop into small pieces.
Watch out for
- Never share salad: it often contains onion and other risky toppings.
- Too much can cause diarrhea.
How much lettuce can a dog eat?
Treats of every kind should stay under 10% of a dog's daily calories, says the World Small Animal Veterinary Association. Here is that daily treat budget by size, and how much lettuce it buys if lettuce is the only treat that day. Lettuce has about 17 kcal per 100 g; 1 cup shredded (47 g) is about 8 kcal.
| Dog size | Daily treat budget | Max lettuce a day |
|---|---|---|
| Small (10 lb) | 26 kcal | 154 g (about 3 cup shredded) |
| Medium (30 lb) | 59 kcal | 349 g (about 7 cup shredded) |
| Large (60 lb) | 100 kcal | 589 g (about 13 cup shredded) |
| Giant (90 lb) | 136 kcal | 800 g (about 17 cup shredded) |
Less is better for small, overweight or diabetic dogs. Work out your own dog's numbers with the dog food calculator. Calories: USDA FoodData Central, Lettuce, cos or romaine, raw.
Other vegetables: quick answers
| Food | Verdict | Short answer |
|---|---|---|
| Asparagus | Avoid | Not unsafe, but not worth it. Asparagus is tough raw and loses most of its value when cooked soft. |
| Mushrooms | Avoid | Store-bought mushrooms are generally fine, but wild mushrooms can be deadly. |
| Tomatoes | Avoid | Best avoided. Ripe flesh is generally safe, but the green parts of the plant contain a toxin. |
| Broccoli | Small amounts | Yes, in small amounts. Cooked florets are easiest on the stomach. |
| Brussels sprouts | Small amounts | Yes, a few cooked sprouts. Expect gas. |
| Corn | Small amounts | Yes, off the cob. The cob can cause a dangerous blockage. |
| Peas | Small amounts | Yes, plain green peas in moderation. |
| Potatoes | Small amounts | Yes, plain and fully cooked, as an occasional extra. Never green or raw. |
Rules for any new food
- Plain is the rule: no salt, butter, oil, onion, garlic, sugar or sweeteners. Most of the danger in human food comes from what is added to it.
- Keep all treats under 10% of your dog's daily calories (WSAVA). The rest should come from a complete dog food.
- Check labels for xylitol, raisins, chocolate and macadamia nuts, which turn up in baked goods, snacks and spreads.
- If your dog has a health condition, such as diabetes, pancreatitis or kidney disease, ask your vet before adding any new food.
Frequently asked questions
Is lettuce safe for dogs?
Yes. Plain chopped lettuce is a safe, watery, low-calorie snack.
How much lettuce can a dog eat?
Treats of any kind should stay under 10% of a dog's daily calories (WSAVA). For a 30 lb dog that is about 59 kcal a day, or roughly 349 g of lettuce if it is the only treat that day.
Sources
- American Kennel Club, "Can Dogs Eat Lettuce?" (updated Sep 24, 2025)
- WSAVA Global Nutrition Committee, "Feeding treats to your dog"
- USDA FoodData Central, SR Legacy (April 2018 release)
Checked October 17, 2026. We are a reference, not a vet: if in doubt, call yours. How we check.