ACORN POISONING: THE FACTS

Acorns, oak leaves and oak branches are poisonous to horses because they contain gallic acid and tannic acid, toxic substances which can cause damage to the liver, kidneys and intestines.

Tolerance levels Every horse has differing tolerances to acorns, which makes it hard to predict how a horse will react to them. Eating a few acorns is unlikely to cause a problem, especially when the horses is also eating a suitable high fibre hay and grass diet. Eating a lot, however, can be toxic.

When Acorn poisoning is rare but can be a particular problem in the autumn for horses who graze near oak trees, as acorns typically fall between September and early November.

Prevention It is important to prevent horses from eating oak leaves, branches or the acorns that fall from the tree, by removing the horses from the field with oak trees, or sectioning off the trees themselves so the horses can’t get near enough to eat what falls from them. Make sure your horse can’t lean over the fence or reach underneath it to get to the acorns.

Symptoms Signs of acorn toxicity include depression, loss of appetite, dehydration, mouth ulcers, colic and constipation. More serious illness can also develop, including diarrhoea, bloody urine and nervous system issues.

Treatment There are no specific antidotes for acorn toxins, so treatment involves treating the clinical signs to minimise organ damage. This can involve putting patients on intravenous fluid therapy to rehydrate them and support kidney function. Electrolytes may be administered, and in some cases antibiotics. Severely ill equine patients may need to be hospitalised for emergency treatment.