Acorns and conkers are a familiar sight on autumn woodland walks, but these seemingly harmless tree fruits can pose a serious risk to your dog.
Acorn poisoning
Thankfully, fatalities from acorn poisoning are rare — but they can occur. Around a quarter of dogs show no symptoms after eating acorns, but those that do can develop anything from mild stomach upset to severe illness, depending on the amount eaten and the dog’s size.
Acorns contain tannins, which are toxic to most animals. The concentration of tannins varies depending on ripeness (green, unripe acorns contain the highest levels) and even between different trees or years.
Symptoms of acorn poisoning usually appear within 1–24 hours after ingestion, although in some cases affecting the liver and kidneys, signs may be delayed. Watch for:
- Vomiting and diarrhoea (sometimes bloody)
- Tummy pain, drooling, lack of appetite or retching
- Red, itchy skin around the mouth or eyes
- Lethargy or restlessness
- Increased thirst or urination (kidney involvement)
- Yellowing of gums, eyes, or skin (jaundice – liver involvement)
If a dog eats many acorns, there’s also a risk of intestinal blockage.
Conker poisoning
Conkers — and all parts of the Horse Chestnut Tree (leaves, bark, flowers) — contain a toxin called aesculin. Like acorns, fatalities are uncommon, but ingestion can still cause serious illness.
Symptoms of conker poisoning often begin within 1–6 hours, but can sometimes take days to appear. Look for:
- Vomiting (most common sign)
- Diarrhoea and tummy pain
- Lethargy or restlessness
- Excessive drooling and thirst
- Wobbliness, tremors, seizures, or collapse
Swallowed conkers can also cause gastrointestinal blockages, especially if swallowed whole.
What should you do if your dog eats acorns or conkers?
If you think your dog may have eaten acorns or conkers, contact a vet as soon as possible. They can assess the risk based on the amount eaten, the time since ingestion, whether they were chewed or swallowed, and any current symptoms.
Treatment options
There is no specific antidote for either acorn or conker poisoning — treatment focuses on managing symptoms and preventing further absorption of toxins.
If ingestion is recent, your vet may Carry out procedures to limit absorption of toxins. If they were eaten some time agon then the vet may:
- Induce vomiting (if safe)
- Perform gastric lavage (stomach wash)
- Administer activated charcoal to bind remaining toxins
- Provide intravenous fluids (“a drip”) to protect the kidneys
- Provide general medical and symptomatic support such as anti-sickness medication pain relief or fluid therapy
- Run blood tests to check liver and kidney function
- In rare cases where a blockage occurs, surgery may be required
Preventing acorn and conker poisoning
Dogs can be quick to grab things they shouldn’t, but these tips can help reduce the risk:
- Keep your dog on a lead in areas with oak or horse chestnut trees, especially in autumn.
- Avoid games involving acorns or conkers.
- Carry a toy or chew to distract them during walks.
- Teach and reinforce “leave it” and “drop” commands — these can be lifesavers.
- If your dog picks up an acorn or conker, remove it safely if you can.
Summary
While acorn and conker poisoning in dogs is rarely fatal, it can still cause significant illness and discomfort. Awareness, prevention, and prompt veterinary advice are key to keeping your dog safe during autumn walks.
Last updated Nov 2025
Vet author: Dr. Ruth Northam
BVSc MRCVS
Ruth is a vet working in collaboration with PawSquad. She has a particular interest in geriatric medicine, pain management and end-of-life care.