Walnut (English walnut)
CautionEnglish walnut kernels are not chemically toxic to dogs, but they are very high in fat, big enough to obstruct, and unusually prone to Penicillium mould that makes tremorgenic mycotoxins. A mouldy walnut is an emergency.
This food guide has not been reviewed by a veterinarian. It summarises general information from sources and should not be used to decide whether a food is suitable for an individual dog or to assess an emergency.
Check before feeding
Check the precautions before sharing
Risk depends on preparation, ingredients or amount. Read the precautions below; body weight alone cannot establish a safe portion.
Signs and health concerns
This list includes both observable signs and conditions identified through examination or testing. It cannot establish the cause or whether an exposure is safe.
- Vomiting
- Diarrhoea
- Abdominal pain
- Tremors
- Poor coordination or balance
- Heightened sensitivity to touch or stimuli
- Involuntary eye movements
- Seizures
More about this food
The walnut itself is not the poison. English walnut kernels contain nothing that chemically intoxicates a dog, and there is no established toxic dose for a fresh nut. What makes walnuts a bad idea is three stacked risks.
Fat comes first. Walnuts are among the fattiest common nuts, and a handful in a small dog buys vomiting, diarrhoea and abdominal pain, with pancreatitis possible at 24 to 72 hours. Refusing food, a hunched or praying posture, and repeated vomiting are the classic pancreatitis picture. Size is second: a whole shelled half or a nut swallowed in the shell can lodge in the oesophagus or intestine, and repeated unproductive retching should be treated as a possible obstruction.
The real hazard is mould. Walnuts support Penicillium growth better than most nuts, and those moulds produce tremorgenic mycotoxins — penitrem A and roquefortine C. Nuts stored a long time, shelled a long time, or picked up off the ground under a tree can carry the toxin without looking obviously spoiled. This is a particular problem in US yards in autumn, where dogs graze on fallen nuts and hulls for weeks. Signs start 30 minutes to 3 hours after ingestion: whole-body tremors, ataxia, hyperesthesia (an exaggerated startle to sound or touch), nystagmus, and seizures.
Call your veterinarian right away if any of that appears, or the ASPCA Animal Poison Control Center at (888) 426-4435 / Pet Poison Helpline at (855) 764-7661. Do not induce vomiting at home, especially in a tremoring dog — aspiration is a real risk and decontamination is a veterinary call. Treatment is sedation, methocarbamol or a similar muscle relaxant, and sometimes intravenous lipid emulsion; signs can persist 24 to 72 hours. The prevention rule is simple: never feed walnuts that have been stored, shelled long, or found under a tree, and rake fallen nuts out of the yard.
Frequently asked questions
- My dog stole one walnut off the counter. Do I need the ER?
- A single fresh, recently shelled kernel in a medium or large dog usually passes uneventfully. Watch 12 hours for vomiting, diarrhoea and appetite. Go in sooner if the dog is small, swallowed it in the shell, or the nut was old or from outside.
- He ate walnuts that fell in the yard. Is that different?
- Yes, and it is the dangerous version. Nuts and hulls that sat on wet ground grow Penicillium and can carry penitrem A. Tremors, wobbliness and seizures typically start within 30 minutes to 3 hours, so call rather than wait for signs.
- Is walnut butter or a walnut-topped brownie safer?
- No. You add sugar and fat to an already fatty nut, chocolate is separately toxic, and some US nut butters are sweetened with xylitol, labelled as birch sugar. Check the label and keep baked goods out of reach.