Common Oak (Quercus robur) habit, mature tree in pasture with sheep© FLPA/REX Shutterstock

Livestock farmers are being warned to be alert to deadly acorn poisoning in their stock, with cattle and sheep most commonly affected.

The warning comes from the RSPCA, which said when food is scarce stock may be forced to eat acorns.

Symptoms of poisoning can start to show within hours or after several days. Symptoms include vomiting and diarrhoea, abdominal tenderness, depression, rapid weight loss, loss of appetite, tiredness and dehydration.

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Farmers suspecting acorn poisoning in their stock should remove the animals from the source, give them plenty of water and contact a vet immediately. The vet might consider washing out the rumen via surgical procedure, although the prognosis is often poor for stock displaying symptoms.

Acorns contain tannins (a type of biomolecule), which get converted to acids in the rumen. These then cause ulcerations in the digestive tract, leading to bloody diarrhoea.

These acids also damage the kidneys, causing them to stop working, so toxins that are normally excreted in the urine build up in the body and cause problems in the brain and the rest of the body, and can ultimately result in death.

Emily Coughlan, RSPCA ruminants scientific officer, said: “Animals are unlikely to gorge on acorns if food is plentiful, so I would advise farmers to ensure food doesn’t get too short in fields with oak trees.

“Monitor the animals and, if some are found to be eating excessive acorns, move them to a different field or fence around the trees to limit their access.”