from the dog health hub
Can Dogs Eat Walnuts? No, and Mouldy Ones Are an Emergency
No. Fresh English walnuts are not strongly toxic, but they are a poor risk: mouldy walnuts (including those picked up under trees on walks) can carry tremorgenic mycotoxins that cause tremors and seizures, black walnuts are toxic to dogs, and all walnuts are fatty, chunky blockage hazards. Not worth it.
Why not
The headline risk is mould. Walnuts, especially ones that have sat in shells, in old bags or on the ground beneath a tree, can harbour moulds producing tremorgenic mycotoxins such as penitrem A. In dogs these cause fine tremors, wobbliness, vomiting and in serious cases full seizures, often within a few hours. Dogs foraging fallen walnuts on autumn walks are the classic case vets see.
Even a clean, fresh walnut is a questionable snack. Walnuts are among the fattiest nuts, so a decent quantity can upset a stomach or trigger pancreatitis in susceptible dogs, and their size and shape make whole nuts and shell fragments a genuine choking and intestinal blockage risk, particularly in small and medium dogs. Black walnuts, less common in UK shops but present in some gardens, are toxic to dogs in their own right.
What to do if your dog has eaten walnuts
- One fresh, plain walnut piece in a healthy large dog is usually nothing to panic about. Watch and move on.
- If your dog has eaten walnuts that could be old or mouldy, or has been scavenging fallen walnuts under a tree, ring your vet or Animal PoisonLine on 01202 509000 without waiting for symptoms.
- Tremors, twitching, wobbliness or seizures after any nut mean an emergency vet visit now.
- If whole nuts or shells went down, watch for blockage signs over the next couple of days: repeated retching, no appetite, no poo.
When to ring the vet
ring your vet if
Fine tremors, twitching or a wobbly, drunken gait · Vomiting or diarrhoea within hours of eating · Repeated retching, refusing food or straining without producing poo · A hunched posture or belly pain in the following day or two
Frequently Asked Questions
My dog ate one walnut from the kitchen. Do I need the vet?
If it was a fresh, plain English walnut and your dog is medium or large, the most likely outcome is nothing at all. Keep an eye out for tummy upset or any twitchiness and ring your vet if either appears, or if your dog is small, prone to pancreatitis, or the nut was in its shell.
Why are fallen walnuts on walks so risky?
Nuts on the ground get damp and mouldy, and some of those moulds produce toxins that attack a dog's nervous system. The nut itself is almost beside the point: it is the mould that puts dogs in hospital. Discourage foraging under walnut trees, especially in autumn.
Is walnut cake or coffee and walnut cake dangerous?
The walnut content of a slice is usually small, but cake brings its own problems: sugar, butter, sometimes chocolate or raisins. Ring your vet if the cake contained chocolate or dried fruit, otherwise watch for an upset stomach and keep cake out of reach in future.
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Open the Dog Health Hub →This article is for information, not diagnosis. If your dog has eaten something worrying, ring your vet or, out of hours, an emergency vet. Every dog is different, and your vet knows yours.