Short answer: Ripe tomato flesh: safe in small amounts — it provides lycopene, vitamin C, potassium, and fiber. Green or unripe tomatoes, stems, leaves, and vines: toxic due to solanine and tomatine, glycoalkaloids concentrated in the plant’s green tissues. The practical danger is a dog gaining access to a backyard tomato plant and eating foliage or unripe fruit — not a dog receiving a slice of ripe tomato as a treat. Pasta sauce, ketchup, and tomato soup are off-limits because of added garlic, onion, and salt, not the tomato itself. When in doubt, call the ASPCA Animal Poison Control Center at (888) 426-4435.

Are tomatoes safe for dogs?

Ripe red tomatoes are considered non-toxic to dogs and can be offered as an occasional treat in small amounts. According to the American Kennel Club, ripe tomatoes are generally safe for dogs in moderation. Nutritionally, ripe tomato flesh delivers modest amounts of lycopene (an antioxidant), vitamin C, potassium, and dietary fiber, all of which can support immune and cardiovascular health. The key word is ripe: as a tomato matures and turns fully red, its levels of the glycoalkaloid tomatine drop significantly, making the ripe fruit safe for most healthy adult dogs in reasonable quantities.

The danger comes from the tomato’s botanical family. Tomatoes belong to the Solanaceae (nightshade) family, which produces natural defense compounds called glycoalkaloids — specifically solanine and tomatine. These compounds concentrate in the leaves, stems, vines, flowers, and unripe green fruit. The ASPCA Animal Poison Control Center lists the tomato plant as toxic to dogs, identifying solanine as the harmful substance. When a dog ingests green tomatoes or foliage, these glycoalkaloids can disrupt normal cellular and neurological function, leading to the clinical signs described below. Ripe fruit is explicitly noted as non-toxic by the ASPCA — the distinction is the green tissues, not the tomato species itself.

How much tomato can a dog eat

For ripe red tomatoes only, a useful guide is: small dogs — 1–2 half-inch cubes; medium dogs — 3–4 pieces; large dogs — 5–6 pieces. All treats, including tomato, should follow the 10% rule: treats make up no more than 10% of a dog’s daily caloric intake. Even ripe tomatoes are mildly acidic and contain natural sugar, so overfeeding can cause gastrointestinal upset in sensitive dogs. Serve only the flesh, and always remove all green parts — stem, leaves, and any green or under-ripe sections — before offering a piece to your dog.

Forms to avoid entirely: green or unripe tomatoes (high in solanine/tomatine); tomato plant parts (leaves, stems, vines, flowers); and pasta sauce, marinara, ketchup, and tomato soup — off-limits not because of tomato itself but because they typically contain garlic, onion, salt, and added sugar, all harmful to dogs. Special populations: puppies, senior dogs, and dogs with kidney disease, diabetes, or a history of GI sensitivity should not receive tomato at all. Dogs on low-potassium diets for certain cardiac conditions should also avoid tomato without veterinary clearance.

Symptoms of tomato or solanine poisoning to watch for

Signs typically appear after a dog eats green tomatoes, leaves, stems, or vines. The ASPCA Animal Poison Control Center lists the following for tomato-plant ingestion: hypersalivation (drooling), loss of appetite, severe gastrointestinal upset (vomiting, diarrhea), depression, weakness, dilated pupils, and slow heart rate. The Pet Poison Helpline adds that larger exposures can cause muscle weakness, tremors, loss of coordination, and irregular heart rhythm. Severe poisoning is uncommon and generally requires ingestion of a substantial quantity of plant material — but smaller dogs are at greater risk from smaller amounts. Call the ASPCA Animal Poison Control Center at (888) 426-4435 or your veterinarian immediately if you observe any of these signs.

What to do if your dog ate green tomatoes or the plant

Stay calm and act quickly. First, remove your dog from the garden or plant to stop further ingestion. Try to estimate how much was eaten and which parts (leaves, stems, unripe fruit, or ripe fruit). If your dog ate only a small amount of ripe red tomato with no green parts and shows no symptoms, monitor closely for 2–4 hours. If your dog ate any green tomatoes, leaves, or stems — regardless of amount — or if any symptoms appear, call the ASPCA Animal Poison Control Center at (888) 426-4435 or the Pet Poison Helpline at (855) 764-7661 right away. Do not induce vomiting unless directed to do so by a veterinarian or poison-control specialist.

Prevention is the most effective strategy for garden-owning households. Use raised beds, wire fencing, or garden barriers to keep dogs out of tomato-plant areas entirely; if your dog is a known digger or explorer, consider a dedicated enclosed garden. When serving ripe tomato safely: wash thoroughly, remove all stems and leaves, cut into small pieces appropriate to your dog’s size, and offer it as an occasional treat — not a meal staple. Cherry tomatoes should be halved to prevent a choking risk in small dogs. Introduce new foods one at a time so any sensitivity or reaction can be identified and attributed clearly.

Frequently asked questions

Are tomatoes toxic to dogs?

It depends on ripeness and which part of the plant. Ripe red tomato flesh is non-toxic and can be given in small amounts — the ASPCA Animal Poison Control Center notes that ripe fruit is non-toxic. However, the tomato plant itself (leaves, stems, vines) and unripe green tomatoes are toxic to dogs due to the glycoalkaloids solanine and tomatine, which concentrate in green tissues. The ASPCA lists the tomato plant as toxic to dogs with solanine as the harmful substance.

What happens if a dog eats a green tomato?

Green tomatoes contain elevated levels of solanine and tomatine, nightshade glycoalkaloids that can cause drooling, vomiting, diarrhea, lethargy, weakness, dilated pupils, and in larger exposures tremors or irregular heart rate, per the ASPCA Animal Poison Control Center and the Pet Poison Helpline. Severity depends on the amount eaten and the dog’s size — small dogs face higher risk from smaller quantities. If your dog ate green tomatoes or plant parts, call the ASPCA APCC at (888) 426-4435 immediately.

Can dogs eat tomato sauce, ketchup, or tomato soup?

No. Processed tomato products are off-limits for dogs — not because of the tomato itself, but because they typically contain garlic, onion, salt, and added sugar, all of which are harmful or toxic to dogs. Garlic and onion belong to the Allium family and can cause hemolytic anemia in dogs even in small amounts. As the AKC notes, plain ripe tomato is safe in moderation, but tomato products with added seasonings should never be fed to dogs. Stick to fresh, plain, ripe tomato flesh only.

For related context, see our Can Dogs Eat Bell Peppers? and Can Dogs Eat Mushrooms?. To check whether your dog’s food contains any of these ingredients, paste the ingredient list into the KibbleIQ analyzer. For methodology context, see our published methodology.