Acorn Poisoning

calendar icon 29 September 2022
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Copyright © NADIS 2002 - 2007

The NADIS data show that acorns are one of the commonest causes of plant poisoning especially late summer in years when acorns are abundant. As the autumn continues with stronger winds and gales the problems are can increase.

Clinical Signs

  • Sudden death can occur (although poisoning generally occurs over a period days)
  • Constipation initially, followed by black watery diarrhoea.
  • Depression and loss of appetite
  • Straining to pass faeces and urinate is very common
  • Weakening, collapse and death (usually within seven days of the onset of signs)
  • The animals have a normal temperature in most cases
  • Acorns can cause birth defects if eaten in sufficient quantities by pregnant cattle Acorns contain gallotannin. In the rumen, gallotannin is broken down to gallic acid and tannic acid. Tannic acid causes ulcerations in the mouth, the oesophagus, and the rest of the intestines. It also damages the kidneys, and it is kidney failure which causes most of the death associated with acorn poisoning. Acorn poisoning will generally affect only a few animals in the herd, as acorn poisoning only occurs if animals eat large amounts of acorns (which will only occur in cattle which develop a taste for them). As tannins concentrate in milk fast-growing calves on heavy-milking dams will often be the first animals to show signs.


  • On the clinical signs described above
  • Finding large amounts of acorns and/or oak leaves at post mortem (although in advanced cases this may not be the case)
  • In live animals, blood and urine tests can identify those with kidney failure


  • There is no specific antidote for acorn poisoning.
  • If the cattle are removed from the acorn pasture in the early stages, most cattle will recover in two to three days
  • Good supportive therapy is the only treatment available: a) Fluid therapy: Oral and intravenous fluids will help keep the kidney functioning b) Broad-spectrum antibiotics to prevent secondary infection c) A single dose of a laxative mineral oil may help in the early stages
  • Cattle that survive are often economically worthless, so euthanasia may be the best option in more severe cases


  1. Feeding 1kg/head/day of calcium hydroxide (hydrated lime) can significantly reduce the risk of poisoning

  2. However, anticipation of outbreaks, fencing off oak trees and removal from pasture are still the best option

Copyright © NADIS 2002 - 2007
NADIS (National Animal Disease Information Service) is a network of 40 veterinary practices and 6 veterinary colleges monitoring diseases in cattle, sheep and pigs in the UK, including BPEX, EBLEX, HCC, QMS, Elanco Animal Health, MLC and Merial

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