Can Dogs Eat Acorns or Horse Chestnuts?

As the colder months roll in, you might be looking forward to those autumnal dog walks full of golden foliage, misty morning light and crunchy leaves underfoot.

There is something else the autumn brings, however, and that’s fallen seeds - including acorns and horse chestnuts that scatter the ground of parks, pavements and fields. Dogs are curious creatures and will gladly munch on acorns and horse chestnuts when your head’s turned - but is it safe for them?

Read on to learn about the dangers of acorns and horse chestnuts for dogs, and tips on how to keep your dog safe on autumn walks.

Are horse chestnuts poisonous to dogs?

Yes - horse chestnuts are toxic to dogs and shouldn’t be ingested.

If your dog eats a horse chestnut, not only does it pose a serious choking hazard, it can make your dog very sick due to the toxin aesculin. This can cause your dog to vomit or have diarrhea - but it can lead to more serious symptoms, or even death if it goes untreated.

What are horse chestnuts?

Let’s talk trees and seeds. A horse chestnut is the seed of a horse chestnut tree, and grows encased in a spiky green shell. The seeds (horse chestnuts) are round, shiny, and brown inside their spiky casing, and are about the size of a large marble or golf ball.

Although horse chestnuts look similar to chestnuts, they are not edible.

How to identify a horse chestnut

On the ground outside, a horse chestnut will likely be inside its green spiky case - though often they can come loose and will resemble a golf-ball-sized seed; which is brown, hard and shiny. Often there will be lots of them on the ground at one time, underneath a horse chestnut tree.

What other parts of the horse chestnut tree are poisonous to dogs?

The entirety of a horse chestnut tree is toxic to dogs if they ingest it.

This includes the bark and flowers, as well as the horse chestnuts. This is because the whole tree contains the toxin, aesculin, which can make a dog very ill or even prove fatal.

Are acorns poisonous to dogs?

Yes, acorns are toxic to dogs due to the presence of tannins.

These are a type of bitter-tasting compound that can irritate a dog’s digestive system and cause pain, diarrhea and vomiting if they eat too many. Tannins also affect the nervous system, so can cause convulsions. In severe cases, tannins can cause kidney or liver damage in your dog.

What are Acorns?

Acorns are the seed of the oak tree.

They are smaller than horse chestnuts, more like a small marble - and are light brown, typically oval-shaped with a hard, smooth shell.

Are acorns poisonous to dogs?

Yes, acorns are toxic to dogs due to the presence of tannins.

These are a type of bitter-tasting compound that can irritate a dog’s digestive system and cause pain, diarrhea and vomiting if they eat too many.

Tannins also affect the nervous system, so can cause convulsions. In severe cases, tannins can cause kidney or liver damage in your dog.

How to identify an acorn

When they’ve fallen from an oak tree, acorns are usually brown, small, hard and shiny. They have a small green cap and maybe a stalk, where they’ve been attached to the branches of the oak tree. Many acorns will scatter the ground underneath an oak tree in the autumn.

How do I know if my dog has eaten something toxic?

Here are some signs that your dog may have eaten something they shouldn’t on an autumn walk…

Mild symptoms of poisoning in dogs

Mild symptoms of poisoning from horse chestnuts or acorns might be:

• Vomiting

• diarrhea

• Lethargy

• Loss of appetite

• Drooling

Severe poisoning symptoms in dogs

Your dog might show the above mild symptoms alongside one or more of these severe symptoms:

• Difficulty breathing

• Tremors or seizures

• Collapse/faint

• Increased heart rate

• Kidney or liver failure (in extreme cases)

When to go to a vet

If your dog shows any of the above symptoms, take them to the vet as a state of emergency. If you notice your dog is eating a horse chestnut or acorn, remove the pieces from your dog’s mouth, if you can. Call a veterinarian or animal poison service promptly, even if the dog currently appears normal. Do not wait for signs to begin.

How many horse chestnuts or acorns will make my dog ill?

There is no safe online number because risk depends on the plant, amount, dog and whether choking or obstruction occurred. Call promptly with the dog's weight, estimated amount, time and current signs. If they eat more than one acorn or horse chestnut, it goes without saying that you should immediately take them to the vet.

How to stop your dog from eating horse chestnuts and acorns

We can’t keep our dog in sight at all times, especially if you’ve let them off the lead - but there are steps you can take to prevent your dog eating acorns or horse chestnuts on an autumn walk:

Keep dog on lead

If you’re in an area that’s rife with dropped acorns and horse chestnuts, it’s a good idea to keep your dog on leash for that portion of the walk. This way it’s easier to keep an eye on them and pull them away from anything they might try to snaffle.

Train them to leave it

Teach your dog commands, if you haven’t already - like ‘leave it!’, to tell your dog to divert their attention away. Whenever you see them sniffling around in grass or underneath a tree that’s dropped its seeds, you can call them away with a stern command.

Be safe outdoors

Keep a sense of safety in mind at all times when you’re out walking the dog during the autumn months - there are lots more seeds and fallen fruits on the ground that your dog can get their nose into. Be vigilant about what they might be distracted by, and keep them distracted with healthy dog treats instead.

Other things to look out for on autumn walks

Here are some other risks to keep a vigilant eye on during your autumn dog walks:

• Wild mushrooms/toadstools. Just like humans shouldn’t eat any mushroom they find, nor should dogs - some are toxic or even deadly.

• Dirty water/puddles. Try to keep your dog from lapping up water from ponds or dirty puddles, as it can contain nasty bacteria or parasites that will make them very sick.

• Ticks. Dogs rolling around in grasses or pushing through shrubs in forests may pick up ticks, which can cause Lyme Disease. Examine your dog’s skin and coat regularly after a walk for any unwanted stowaways.

• Lungworm. Snails, slugs, and their slime trails can transmit lungworm, a parasite that can cause serious illness in dogs. This one is tricky, but try to stop your dog from slurping up slugs and snails

There's nothing better than enjoying the turn of the season with your dog! And with our help, you can do so safely. For more tips on keeping your dog safe, happy and healthy, be sure to check out the rest of our Dog Blog.

To make sure they're chomping on nothing but nutritious goodies, explore our whole healthy and natural dog food range.