From September, oaks, horse chestnuts and walnut trees drop their crop onto South Surrey lawns and paths, and some dogs eat them. Acorns and horse chestnuts can cause vomiting and diarrhea, and a whole nut can block the gut in a small dog. Mouldy walnuts are the serious one: they can cause tremors within hours.
Why this is an autumn problem
Mature trees are one of the nicest things about South Surrey streets, yards and parks, and in autumn they shed everything at once. Nuts collect in the grass, roll into gutters and get carried into yards by squirrels. A dog who ignores them all summer suddenly has a lawn full of interesting objects to chew.
Young dogs and dedicated scavengers are the usual culprits, but boredom on a wet day turns plenty of sensible dogs into foragers. Many swallow one or two with nothing worse than a brief upset. The trouble comes from quantity, from size, and from nuts that have started to rot.
The three to know
Acorns
Acorns contain tannins, bitter compounds that irritate the stomach and gut. A dog who eats a few may vomit, have diarrhea or refuse food for a day. Large amounts are harder on the body, and in rare cases have affected the kidneys. The caps and hard shells can also scrape the mouth, and a handful of whole acorns can sit in the stomach or lodge further down.
Horse chestnuts
Horse chestnuts, which many people know as conkers, are the shiny brown nuts inside a spiky green case. They contain compounds that cause drooling, vomiting, diarrhea and a sore belly, usually within a few hours, and some dogs are restless or wobbly. A horse chestnut is also exactly the size to block the intestine of a small or medium dog, and the spiky case can injure the mouth.
Horse chestnuts are not the same as the sweet chestnuts people roast. Many owners cannot tell the two apart on the ground, so it is safest to regard any chestnut your dog eats as a horse chestnut until you know otherwise.
Walnuts, especially mouldy ones
Walnuts that have been lying in wet grass grow moulds on the husk and shell. Some of those moulds produce toxins that act on the nervous system, and signs can start within an hour or two: trembling, twitching, panting, an unsteady walk and, in serious cases, seizures. Black walnut hulls also irritate the gut on their own. A dog who has eaten old walnuts and starts to shake needs to be seen straight away.
What you might notice, and when
- Within a few hours: drooling, vomiting, diarrhea, licking the lips, eating grass
- Within an hour or two of mouldy nuts: trembling, restlessness, panting or overheating, wobbliness
- Over the following days, sometimes longer: repeated vomiting, a tense or painful belly, refusing food, straining with little or no stool, which can all point to a blockage
Blockages are the reason not to wait for a nut to pass on its own. A nut or shell stuck in the intestine gets more dangerous the longer it stays there, and pet diagnostics such as X-rays help us see what is going on. Some cases need our surgical services team to remove the object.
If your dog has eaten nuts
- Take away what is left and keep a sample, or take a photo of the nut and the tree it fell from.
- Estimate how many your dog ate and when, and note your dog’s weight.
- Phone us. For a single acorn in a large dog, we may simply ask you to watch. For horse chestnuts, a handful of anything, or any mouldy walnut, we will usually want to see your dog.
- Do not make your dog vomit at home. Hard nuts and spiky cases can do more damage on the way back up.
Shaking, seizures, repeated vomiting or a sore, tight belly are an emergency for our urgent care team. We are open Monday to Saturday from 09:00 AM to 10:00 PM and Sunday from 10:00 AM to 06:00 PM. Outside those hours, take your dog to the nearest open emergency hospital instead.
Cutting down the temptation
- Rake under your own trees every few days while they are dropping, and bag the nuts rather than leaving piles.
- Walk on a shorter leash under oaks and chestnuts in October, and keep moving past the spots your dog likes to forage.
- Practise “leave it” and “drop it” with a reward that beats a nut.
- Watch the compost and yard waste bins, where rotting nuts and husks collect.
- Check the car and porch after walks with children, who tend to fill their pockets with horse chestnuts.
Autumn trees are not the only seasonal temptation for a scavenger. Our guide to summer BBQ and picnic food hazards in South Surrey covers the foods that cause similar trouble at other times of year.
Frequently asked questions
My dog ate one acorn. Should I worry?
Usually not. One acorn in a medium or large dog tends to cause, at most, a mild stomach upset. Phone us if your dog is small, ate several, or starts vomiting repeatedly or refusing food.
Are horse chestnuts more dangerous than acorns?
They are more likely to cause a noticeable upset, and their size makes them a real blockage risk for smaller dogs. Any dog who has eaten a horse chestnut is worth a phone call.
Why are mouldy walnuts singled out?
Because the moulds that grow on them can produce toxins that cause tremors and seizures, sometimes quickly. That is a different kind of problem from a stomach upset and needs to be seen right away.
What about cats?
Cats are rarely affected, because they seldom eat nuts. If a cat chews one and then vomits or seems unwell, phone us all the same.
Are sweet chestnuts safe for dogs?
Plain, cooked sweet chestnuts in small amounts are generally fine. The trouble is telling them apart from horse chestnuts on the ground, and the spiky cases hurt either way. If you are not sure which one your dog ate, assume it was a horse chestnut.
My dog keeps eating nuts on walks. What else can I do?
Choose routes away from heavy nut trees in October, carry high-value rewards for good choices, and consider a well-fitted basket muzzle with a scavenging guard for a determined forager. It still lets a dog pant and drink.
Speak to the team at Elgin Park Animal Hospital
If your dog has eaten horse chestnuts, acorns or old walnuts, phone us, or go to the nearest open emergency hospital when we are closed.
Published by the team at Elgin Park Animal Hospital.
This article is for general educational purposes only and is not a substitute for an in-person veterinary examination or advice about your individual pet. If you have an urgent concern about your pet, contact Elgin Park Animal Hospital or your nearest emergency veterinary hospital right away.
Elgin Park Animal Hospital
Unit 103, 3010 148 Street, Surrey, BC V4P 0G8
Phone: (604) 531-3394
Email: info@elginparkvets.ca
Hours: Monday to Saturday 09:00 AM – 10:00 PM; Sunday 10:00 AM – 06:00 PM