Can Cats Eat Walnuts?

Not recommended. Walnuts are not a good treat for cats because they are fatty, can upset the stomach, and moldy walnuts can contain dangerous mycotoxins.

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Monitor at Home

Walnuts are risky and best avoided for cats

Walnuts are not considered an ideal or recommended food for cats. While ASPCA lists black walnut as non-toxic to cats, walnuts are high in fat and oils, may cause vomiting or diarrhea, and moldy walnuts can expose cats to harmful tremorgenic toxins.

How urgent is this?

Emergency

Go to the ER now

  • ● Your cat ate moldy walnuts or walnuts picked up from the ground outdoors
  • ● Tremors, seizures, collapse, severe weakness, or trouble walking after eating walnuts
  • ● Repeated vomiting, severe lethargy, or difficulty breathing
Urgent

See a vet within 24 hours

  • ● Your cat ate multiple walnuts or walnut pieces with shells
  • ● Vomiting, diarrhea, drooling, belly pain, or refusing food after eating walnuts
  • ● Your cat has a history of pancreatitis or other digestive disease and ate walnuts
Monitor

Watch at home, call if it worsens

  • ● Your cat ate a tiny amount of plain fresh walnut and seems normal
  • ● No symptoms develop over the next several hours
  • ● You can confirm the walnut was not moldy, seasoned, chocolate-coated, or mixed with other toxic ingredients

Why Walnuts Are Dangerous for Cats

Cats are obligate carnivores, so walnuts do not offer meaningful nutritional benefits for them. The biggest concerns are digestive upset from the high fat content, possible pancreatitis risk in sensitive cats, choking or intestinal irritation from shell fragments, and poisoning if the walnut is moldy and contaminated with mycotoxins.

  • High fat and oil content can cause stomach upset such as vomiting or diarrhea
  • Moldy walnuts can contain tremorgenic mycotoxins that may cause tremors or seizures
  • Shells are a choking hazard and may irritate the digestive tract
  • Seasoned, salted, candied, or chocolate-covered walnuts add extra risks for cats
  • If your cat eats walnuts and you are unsure whether they were fresh or moldy, call your vet
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Common Questions

Are walnuts toxic to cats?
Plain walnuts are not generally considered highly toxic to cats, and ASPCA lists black walnut as non-toxic to cats. However, walnuts are still not recommended because they are fatty, can cause digestive upset, and moldy walnuts may carry dangerous toxins.
How is walnut risk different for cats versus dogs?
Dogs are more commonly reported to develop serious problems from black walnuts and moldy walnuts, including tremors and seizures. In cats, black walnut itself is listed by ASPCA as non-toxic, but cats can still become sick from eating fatty nuts, shell material, or mold-contaminated walnuts. Because cats are smaller, even a modest amount may be more significant.
Can cats eat a small piece of plain walnut?
A very small piece of fresh, plain walnut is unlikely to cause poisoning in most cats, but it is still not a good treat choice. There is no established safe serving size for cats, so it is best not to intentionally feed walnuts.
What symptoms can happen if a cat eats walnuts?
Possible signs include vomiting, diarrhea, drooling, reduced appetite, and lethargy. If the walnuts were moldy, more serious neurologic signs such as tremors, incoordination, or seizures can occur and require immediate veterinary care.
Should I make my cat vomit after eating walnuts?
No. Do not induce vomiting unless a veterinarian specifically tells you to do so. Instead, remove access to the walnuts, note how much was eaten and whether mold or shells were involved, and call your vet for guidance.

Sources

  1. Black Walnut — ASPCA
  2. People Foods to Avoid Feeding Your Pets — ASPCA
  3. Tremorgenic Neuromycotoxicosis in Dogs — Merck Veterinary Manual
  4. Pancreatitis in Dogs and Cats — Merck Veterinary Manual

Disclaimer: The information provided in this article is for educational purposes only and does not constitute veterinary medical advice. Reading this content does not establish a veterinarian-client-patient relationship. Every pet is different — always consult a licensed veterinarian before making decisions about your pet's health, diet, or care. If you'd like personalized guidance, you can talk to one of our vets. If your pet is experiencing a medical emergency, contact your local emergency animal hospital immediately.

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