Acorns are toxic to your dog. Please beware during forest walks!

Written by Anne | October 27, 2026

Autumn has started and acorns are falling off the threes in bunches. A lot of dogs find it amusing and fun to play with these oak nuts and can sometimes even eat them. Please beware of this as a pet owner, because acorns contain a toxic substance!

Acorns and Dogs

Not all dog owners know that the chewing of eating of acorns is toxic and can be dangerous to their dog. Oak nuts and oak leaves contain a toxic substance called tannic acid. When your dog consumes a lot of tannic acid, this will cause stomach issues, diarrhoea and vomiting. Unfortunately, in extreme cases, an overdose can even lead to renal failure and death as a result. So keep this in mind when making your forest walk!

Tannic acid is not the only reason why acorns are dangerous to dogs. When sharp oak nuts are consumed, the intestines can get constipated. Furthermore, the thin membrane which surrounds the intestines can also be irritated by the sharp edge of these nuts.

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Pine cones and dogs

Pine cones and chestnuts (Castanea sativa) are not toxic, which means they don’t contain a poisonous substance. However, these are often swallowed by dogs while playing in the park or forest. Pine cones and chestnuts can also lead to constipation and gastrointestinal issues. This sometimes leads to mandatory surgical procedures. Vetsend recommends you to teach your dog not to play with pine cones or chestnuts. You can learn your dog commands such as “drop it” or “leave it” to prevent this from happening.

Horse chestnuts (Aesculus hippocastanum) are poisonous though.

Watch out for poisonous mushrooms

In addition to acorns, mushrooms are another autumn hazard for dogs. Some mushrooms are highly toxic, even in small amounts. Examples include the fly agaric, death cap, deadly webcap and devil’s bolete. Because it is difficult to distinguish between poisonous and non-poisonous species, it is important never to allow your dog to nibble on or sniff mushrooms.

Symptoms of mushroom poisoning can range from vomiting, diarrhoea and abdominal pain to severe damage to the liver, kidneys or nervous system. Has your dog eaten a mushroom? Contact your vet immediately so that appropriate measures can be taken. In autumn, it is wise to keep your dog on a lead in areas where many mushrooms grow, especially if your dog tends to eat things outside.

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Are you looking for more products to keep your dog healthy, then have a look at our dogs category.

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