Why it's dangerous
The green parts of the plant contain solanine, a glycoalkaloid that acts as a toxin when ingested in large quantities, though it rarely causes severe poisoning in small animals.
Toxic compound: Solanine
How vets treat it
No treatment plan written for cats was found. PetMD says the signs are often uncomfortable for a cat and should be treated quickly. For dogs, Pet Poison Helpline describes decontamination soon after a meaningful amount of green plant material, then supportive care such as fluids, anti-nausea medicine and close monitoring.
Outlook
No recovery figures for cats were found. PetMD says tomato poisoning is not normally fatal in cats, but the signs it causes should be treated quickly.
Where pets are exposed
- Tomato plants (Solanum lycopersicum) in vegetable gardens, raised beds and containers. Tomatoes belong to the nightshade family, along with potatoes, peppers and eggplants.
- The leaves, stems, vines and flowers. They contain the glycoalkaloids tomatine and solanine, which act as the plant's natural defense.
- Green, unripe tomatoes, on the vine or fallen on the ground. Many dogs love green tomatoes, and they don't always sit well.
- Green stems and leaves still attached to a ripe tomato, including cherry and grape tomatoes.
- Compost bins that hold green tomatoes or tomato plant clippings.
- Ripe, red tomatoes have the least of these compounds and are considered non-toxic. In a 1995 lab study, red tomatoes contained 0.03 to 0.08 mg of tomatine per 100 g, green tomatoes 0.9 to 55 mg, and the leaves, stems, flowers and roots 14 to 130 mg.
Prevention
- Fence off the vegetable garden, or grow tomatoes in raised beds or in containers your pet can't reach.
- Pick up green or partly ripe tomatoes that fall from the vine, and check the garden often in summer, when plants carry the most unripe fruit.
- Keep compost in a closed bin your pet can't get into. Green tomatoes and plant clippings can end up there.
- If you share a ripe tomato with your dog, choose a fully red one, remove every green stem and leaf, keep the portion small and serve it plain, without salt, garlic or onion.
- Teach your dog a "leave it" cue for garden plants, as a backup to fencing.
- Keep cats away from tomato plants, and skip tomatoes as a treat: cats get little from them.
Good to know
The ripened fruit is considered non-toxic; toxicity is primarily associated with the green parts of the plant and requires large ingestions.
Common questions
Can dogs eat tomatoes?
Ripe, red tomatoes, yes, in small amounts. Pet Poison Helpline says ripe tomatoes are generally safe for dogs in moderation, and a slice or a few cherry tomatoes is plenty for most dogs. Remove any stem or leaves first, and don't share tomatoes cooked with salt, garlic or onion. The green parts of the plant, including unripe tomatoes, are toxic, so call your vet or a pet poison line if your dog ate them.
Are tomatoes toxic to cats?
Ripe tomato fruit isn't toxic to cats, but the plant and unripe fruit are. The ASPCA lists the tomato plant as toxic to cats, and PetMD says even a small amount of the plant can cause signs such as drooling, vomiting, loss of appetite and dilated pupils. Very small amounts of plain, ripe tomato are safe, but cats get little from them, so tomatoes are best avoided. Call your vet if your cat chewed a tomato plant.
Which parts of a tomato plant are poisonous?
The leaves, stems, vines, flowers and unripe green tomatoes. They contain tomatine and solanine, and the levels drop as the fruit ripens. In a 1995 lab study, the leaves, stems, flowers and roots contained 14 to 130 mg of tomatine per 100 g, green tomatoes 0.9 to 55 mg, and red tomatoes only 0.03 to 0.08 mg. Ripe, red tomatoes are considered non-toxic.
My dog ate green tomatoes or tomato leaves. What should I do?
Note which parts your dog ate, roughly how much and when, and your dog's weight, then call your vet or a pet poison line, even if your dog seems fine. Severe poisoning is relatively uncommon, because a dog would typically need to eat a significant amount, but smaller amounts can still cause vomiting, diarrhea, drooling or lethargy, particularly in small dogs. Larger amounts can cause weakness, tremors, loss of coordination and changes in heart rate.
Are cooked or fried green tomatoes safe for pets?
No source says they are. A 1995 lab study found that microwaving and frying did not significantly change tomatine levels, and it measured high levels in fried and pickled green tomatoes. Cooked tomato dishes also often contain garlic, onion and salt, which are harmful to dogs. Keep green tomato dishes away from your pet.
Can my dog or cat have tomato sauce or ketchup?
For dogs, Pet Poison Helpline says small amounts are fine. Plain tomato sauce and ketchup are unlikely to contain enough garlic or onion to cause concern, but they are high in salt and sugar, so check the label for garlic and onion, including powders. For cats, PetMD advises against tomato sauce, because it usually contains ingredients that can harm cats, such as garlic, onion and salt.
Sources
- ASPCA Animal Poison Control Center — Toxic and Non-toxic Plants: Tomato Plant
- Pet Poison Helpline — Tomato
- Pet Poison Helpline — Are Tomatoes Bad for Dogs? What's Safe and What's Toxic
- Pet Poison Helpline — Tomato Toxicity: What You Need to Know
- Pet Poison Helpline — Vegetable Gardening and Pets
- Pet Poison Helpline — Emergency Instructions
- PetMD — Can Cats Eat Tomatoes? (Sandra C. Mitchell, DVM, 2024)
- Journal of Agricultural and Food Chemistry (abstract via FAO AGRIS) — Friedman M, Levin CE. alpha-Tomatine content in tomato and tomato products determined by HPLC with pulsed amperometric detection (1995)
- Pet Poison Helpline
This page is informational and is not veterinary advice. If your pet has been exposed to something risky, contact your vet or an animal poison control line right away.
