Are Tomatoes Poisonous to Dogs?

This is a conditional case. The ASPCA classifies the TOMATO PLANT as toxic to dogs (toxic principle: solanine), but explicitly notes that 'ripe fruit is non-toxic.' The harmful glycoalkaloids (solanine and tomatine) are concentrated in the green parts of the plant — leaves, stems, vines, flowers, and unripe green fruit — and drop to negligible levels as the fruit ripens and turns red. SAFE: small amounts of plain, fully ripe (red) tomato flesh, with the stem and any green portions removed, fed occasionally as a treat. NOT SAFE: green/unripe tomatoes, tomato leaves/stems/vines (a real risk for dogs with garden access), and tomato-based prepared products such as pasta/pizza sauce, ketchup, and sun-dried or seasoned tomatoes, which commonly contain onion, garlic, salt, sugar, or xylitol — all of which pose their own toxicity or GI risks to dogs. Introduce new foods in tiny quantities; even ripe tomato can cause GI upset (the fruit is acidic) in sensitive dogs or those with existing GI conditions. Watch for choking on whole cherry/grape tomatoes in small dogs. When in doubt, avoid, and contact a vet or the ASPCA Animal Poison Control Center (888-426-4435) or Pet Poison Helpline (855-764-7661) for any ingestion of green plant material.

If your dog ate a risky form — the peel, seeds, pit, green/raw parts, or a product containing xylitol — treat it as urgent: call your vet, the ASPCA Animal Poison Control Center (888) 426-4435, or the Pet Poison Helpline (855) 764-7661.