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Is Horse Chestnut Toxic to Cats?

☠️ ToxicSeverity: Moderate
✅ Cross-checked against veterinary poison-control guidance · Oct 2026 audit
⚠️ Educational info only. If your pet just chewed something and looks unwell, skip the reading and call your vet or Pet Poison Helpline (US): (855) 764-7661.
Yes, horse chestnut is toxic to cats. The shiny brown conkers, leaves and sprouts contain aesculin and saponins that inflame the gut and stress the nervous system.

Also known as: Conker Tree, Aesculus · Aesculus hippocastanum

What makes it toxic

Aesculin plus aescin-type saponins concentrated in the conkers and young growth. They irritate the GI tract and in larger doses affect nerves and blood.

Warning signs to watch for

Drooling, vomiting, diarrhea, depression and thirst within hours. Significant ingestions can add tremors, staggering and dilated pupils.

What to do if your cat eats it

Remove the conker or plant material and offer water. Call your vet the same day for confirmed ingestion; tremors or collapse mean an ER visit.

Common questions

Is one conker dangerous to a cat?

A chewed conker can cause real vomiting and diarrhea in a cat. Treat even a single conker as worth a vet call.

Is horse chestnut the same as edible chestnut?

No. Sweet chestnuts are edible, but horse chestnut conkers are toxic to people and pets alike. Never confuse the two.

More plants checked for cats

Pothos☠️ ToxicYes, pothos is toxic to cats. Chewing the leaves or vines releases sharp calcium oxalate crystalAloe Vera⚠️ Mildly ToxicAloe vera is mildly to moderately toxic to cats. The gel is famously soothing for human skin, buSpider Plant✅ Non-ToxicNo, spider plants are non-toxic to cats. They are one of the best houseplants for homes with curEaster Lily☠️ ToxicYes — and this is one of the most dangerous plants a cat can meet. Every part of an Easter lily,Sago Palm☠️ ToxicYes — sago palm is severely toxic to cats and among the deadliest houseplants. Every part contaiBoston Fern✅ Non-ToxicNo, Boston ferns are non-toxic to cats — a classic choice for plant-loving cat households.

This page is general educational information, not a substitute for professional veterinary advice. Every pet is different — if your animal ate something concerning, contact your veterinarian or a pet poison hotline right away. Checking what your pet can eat? Visit our sister site SafeOrToxic.