Last reviewed: August 2026

Can Dogs Eat Walnuts?

ToxicEspecially If Mouldy

Fresh walnuts in small amounts carry mainly a fat and choking risk, but mouldy walnuts (including those found on the ground under a tree) can contain tremorgenic mycotoxins that cause serious neurological symptoms.

Why

The real danger with walnuts specifically is mould — walnuts that have started to decompose, especially those found outdoors under a tree, can develop mycotoxins that cause tremors and seizures in dogs. This is a meaningfully higher risk than most other nuts, which is why walnuts get their own toxic classification rather than sharing the general 'moderate' nut caution.

Symptoms to watch for

Timing	What to expect
Hours after mouldy walnut ingestion	Tremors, seizures, elevated temperature, vomiting — signs of mycotoxin exposure

What to do if your dog ate this

Never allow access to walnuts found on the ground, especially old or mouldy ones
Keep walnut trees fenced off from dogs if you have one on your property
Fresh, shelled walnuts in tiny amounts are lower risk but still not recommended given the fat content and choking hazard
See our moldy food page for the broader mycotoxin mechanism this shares with mouldy bread, cheese, and compost

🚨 If this happens

Contact your nearest 24-hour emergency vet clinic immediately, or your regular vet's after-hours line. Bring packaging if you have it.

ASPCA Animal Poison Control (US, reference only): +1-888-426-4435 — typically charges a consultation fee for non-US callers.

Sources

General veterinary toxicology consensus, cross-referenced against the Merck Veterinary Manual and ASPCA Animal Poison Control Center food hazard references. See How We Source This for our methodology.

This page is general educational information, not a substitute for veterinary advice.