Acorn poisoning and the risk to livestock

01 October 2025

Cattle in a field

Livestock farmers are being warned to be alert to deadly acorn poisoning in their stock during the autumn/winter months, with cattle and sheep most commonly affected. Pigs are more tolerant and poisoning is rare.

With acorn numbers particularly high this year, NFU Cymru is urging farmers to be especially vigilant and to move animals away from areas with large numbers of acorns, fallen leaves and twigs, or fence off the area to restrict access.

Acorns contain gallotannin which gets broken down to gallic acid and tannic acid. This can cause ulcers in the digestive tract, kidney failure causing them to stop working, which can result in death. Acorns can also cause birth defects.

Symptoms

Symptoms of poisoning can start to show within hours or after several days.

Symptoms are progressive and begin with a lack of appetite, constipation, which is followed by small quantities of dark coloured faeces, which may contain blood.

The animal experiences:

  • Abdominal pain
  • Breathing difficulties
  • A weakening pulse
  • Mucous membranes becoming pale
  • Convulsions may be seen before death

 

“With an abundance of acorns dropping this year, we’re urging livestock farmers to be particularly vigilant and report any suspected cases to their vet immediately.”
Tori Morgan, NFU Cymru National Policy Adviser

 

What to do if acorn poisoning is suspected

Farmers suspecting acorn poisoning in their stock should remove the animals from the source, give them plenty of water and contact a vet immediately.

 


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