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Is Walnut Tree 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, walnut is toxic to cats. The nuts, hulls and foliage contain irritant compounds, and moldy fallen walnuts are the most dangerous form.

Also known as: English Walnut, Black Walnut · Juglans spp.

What makes it toxic

Juglone and other phenolic irritants in hulls, leaves and nuts. Mold growing on fallen husks can add tremorgenic mycotoxins, the worst hazard.

Warning signs to watch for

Vomiting, diarrhea and drooling after fresh nut or leaf chewing. Moldy husk ingestion can add tremors, panting, fever and seizures.

What to do if your cat eats it

Remove plant material and note which part was eaten. Call your vet for any confirmed ingestion; tremors or panting after moldy husks mean an immediate ER visit.

Common questions

Why are moldy walnuts so dangerous to pets?

Fungi growing on fallen husks produce tremorgenic mycotoxins that cause tremors and seizures. Moldy walnuts are far riskier than the fresh nut itself.

Is the black walnut worse than English walnut for cats?

Black walnut is generally considered more toxic, and its fallen hulls mold readily. Treat both species as unsafe.

More plants checked for cats

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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.