Oak (Quercus): Poisonous Plant Of The Month

Learn more about oak poisoning and the signs to look out for.

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One of the more common plant toxicities we deal with is oak poisoning, from both leaves and acorns. The disease occurs at two times of the year, spring and autumn. In both seasons poisonings tend to be seen after a storm or particularly high winds. Fallen trees or lots of acorns on the ground are a major risk factor. The animals most at risk are usually those on a restricted diet or restricted grazing. This makes them much more likely to eat toxic doses of young leaves or acorns.

Clinical disease is seen 3-7 days after the animal has eaten the oak, which causes gut damage and kidney failure. Both cattle and sheep are vulnerable. There is often a high rate of mortality – up to 70%.

If the animal survives the initial disease it can take up to 60 days to regain good health. Another possible side effect of oak consumption is in pregnant cows – if the pregnancy is between 3 and 6 months then it is possible the cow will abort or the calf will be born deformed.

Early treatment is essential to maximise survival rates in affected animals. Whether the animal survives or not may be more down to the quantity of oak eaten rather than the treatment, so euthanasia on welfare grounds may occasionally be the most appropriate treatment.

Symptoms of Oak Ingestion

Signs to look out for where oak may have been ingested are as follows:

  • Off feed
  • Depression
  • Poor/losing condition
  • Dehydration
  • Straining
  • Drinking/urinating more
  • Mucoid or bloody diarrhoea
  • Death

Out of hours emergency

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