RSPCA urges farmers, smallholders, and dog owners to be aware of the signs and symptoms of acorn poisoning this autumn.
Although an important source of food for many birds and some mammals, parts of the tree are extremely poisonous to livestock and pets.
Many animals are susceptible to the poisoning, but cattle and sheep are affected most often. However, horses and dogs can become very ill if they consume acorns or oak leaves.
If animals eat young oak leaves, during the spring, or acorns, during the autumn, symptoms of poisoning can begin to display within hours or after several days.
However, if you are concerned that your animal has eaten anything that could be poisonous, rather than waiting for any symptoms to appear, you should consult a veterinary surgeon immediately.
Symptoms of acorn poisoning may vary between species, but include vomiting and diarrhoea, abdominal tenderness, depression, rapid weight loss, loss of appetite, tiredness and dehydration.
Dr Emily Coughlan, the RSPCA’s ruminants scientific officer, said: “Animals are unlikely to gorge on acorns if food is plentiful so I would advise farmers and horse owners to ensure food does not get too short in fields with oak trees.
“Monitor the animals and, if some are found to be eating excessive acorns, then move them to a different field or fence around the trees to limit their access.”
Although rarely reported, according to the Veterinary Poisons Information Service (VPIS), there have been some cases of severe acorn poisoning in horses. They can suffer from a range of symptoms, including colic, haemorrhagic diarrhoea, weakness, head pressing, and incoordination.