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Walnuts: Toxic — Do Not Feed

Black walnuts are toxic to dogs and can cause tremors and seizures. English (grocery-store) walnuts are not directly toxic but frequently harbor mold that produces tremorgenic mycotoxins — making them dangerous anyway. Avoid all walnuts for dogs.

Emergency — Call Poison Control If Your Dog Ate WalnutsASPCA Animal Poison Control: (888) 426-4435
Pet Poison Helpline: (855) 764-7661
Go to an emergency vet immediately if your dog shows tremors, seizures, or vomiting after eating walnuts.

Why Are Walnuts Dangerous for Dogs?

There are two types of walnuts and two separate dangers:

Black Walnuts

The hulls of black walnuts contain juglone, a compound that is directly toxic to dogs and horses. Juglone poisoning can cause lethargy, vomiting, diarrhea, and neurological symptoms. Black walnuts are commonly found fallen in yards.

English Walnuts (Store-Bought)

English walnuts are not inherently toxic, but they are highly susceptible to Aspergillus mold, which produces tremorgenic mycotoxins. Even slightly old or poorly stored walnuts can carry enough toxin to cause severe neurological reactions in dogs. Because you cannot visually detect this mold, even fresh-looking walnuts carry risk.

Symptoms of Walnut Toxicity in Dogs

  • Vomiting (often within minutes)
  • Muscle tremors
  • Seizures
  • Weakness or incoordination (ataxia)
  • Panting or fever
  • Diarrhea

Symptoms from mycotoxin exposure typically appear within 30 minutes to 3 hours of ingestion.

What to Do If Your Dog Eats Walnuts

  1. Do not wait for symptoms to appear before calling a vet
  2. Call ASPCA Poison Control (888-426-4435) or your emergency vet
  3. Note: how many walnuts, what type (black vs. English), and the time eaten
  4. Bring any packaging or a sample of the walnuts to the vet

Can dogs eat English walnuts from the grocery store?
Technically they are not directly toxic, but the mold risk (tremorgenic mycotoxins) is high enough that vets universally advise against giving dogs any walnuts.

My dog ate one walnut. Should I panic?
One small walnut from a sealed, fresh bag is unlikely to cause serious harm to a large dog. Monitor closely for 4–6 hours and call your vet if any symptoms appear. Small dogs warrant an immediate vet call.

Are black walnuts found in yards dangerous?
Yes. Black walnut hulls contain juglone which is directly toxic to dogs. Keep your dog away from black walnut trees and clean up fallen nuts immediately.

Can dogs eat walnut oil?
Small amounts of pure walnut oil are unlikely to cause the mycotoxin risk (the toxin is in the nut meat and hull, not extracted pure oil), but it offers no health benefit to dogs and is high in fat. Skip it.

More dog food safety guides:

This article is for general information only and is not a substitute for professional veterinary advice. If your dog is unwell or you have a medical concern, contact your veterinarian. In an emergency, call the Pet Poison Helpline (855-764-7661) or ASPCA Animal Poison Control (888-426-4435).
DE
DoggleLife Editorial Team
Contributor at DoggleLife

The DoggleLife editorial team researches and writes practical, evidence-based dog-care guidance, citing veterinary and scientific sources. Always consult your own veterinarian for medical decisions about your dog.

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