Be on the lookout for acorn poisoning this autumn

It is a bumper year for some fruits, nuts and seeds, producing a feast for wildlife. However, the glut of acorns brings with it an increased risk of acorn poisoning in livestock.

Outbreaks of acorn poisoning tend to occur after stormy weather, when large numbers of acorns fall from trees. However, it can also arise in mast years – when nature produces a bumper crop.

Though cattle and sheep are most affected, many livestock species can suffer from acorn poisoning; mortality rates can be as high as 70%.

A period of feed restriction before exposure plays a key role in increased susceptibility of animals.

Key facts

• Acorns and oak leaves contain phenols and tannins that are toxic when ingested in large quantities
• Young leaves are more toxic than mature ones
• Cattle and sheep are more commonly affected by these compounds, which lead to kidney failure
• Pigs are generally more tolerant of the effects

Clinical signs

Animals can develop a variety of clinical signs, which usually occur three to seven days after consuming a toxic dose.

Signs may include:

• Loss of appetite
• Depression
• Excessive drinking or dehydration
• Excessive urination
• Blood in urine
• Jaundice (yellowing of skin)
• Constipation, followed by black tarry faeces and diarrhoea
• Swelling of the chest and abdomen (bloat)
• Death – severely affected animals die within 24 to 72 hours
• Malformed calves and abortions

Contact your vet for advice, as diagnosis is based on clinical signs, history, blood tests, post-mortem examination of the kidneys and ruling out other causes.

Treatment

There is no specific treatment.

Contact your vet for advice in the first instance – early action is key.

If you or your vet suspect acorn poisoning, remove animals from the source immediately, minimise stress and ensure animals have good access to fresh water to prevent dehydration.

Severely affected animals that survive may lose weight and fail to thrive.

With limited treatment options, early action and prevention are key.

Prevention

Management plays a key role in preventing acorn poisoning. 

Check fields with oak trees daily, particularly following storms where large quantities of green acorns may be blown to the ground.

Move livestock away where acorn fall is heavy.

If it is not possible to move livestock away from or to remove acorns, provide attractive alternative food sources so they will be less likely to consume large quantities of acorns.