
21/08/2025
𝐀𝐜𝐨𝐫𝐧 𝐏𝐨𝐢𝐬𝐨𝐧𝐢𝐧𝐠
Some sources indicate that 2025 is likely to be a mast year. A mast year is when trees, particularly oak and beech, produce a large crop of fruits and nuts (mast). While this is great for Mother Nature, it brings a fresh risk to our equids, in the form of Acorn poisoning.
Acorns and Oak leaves contain a substance called tannic acid and can cause serious illness if ingested in a sufficient quantity. Horses will not usually choose to eat acorns due to their bitter taste, however, if their pasture is bare, they may ingest acorns as they forage for food. This can be caused by overgrazing or long, hot summers as we have had this year. Whilst eating a very small amount of acorns is almost harmless, they can also be addictive with horses actively searching for them.
𝐏𝐫𝐞𝐯𝐞𝐧𝐭𝐢𝐨𝐧: To prevent acorn/leaf ingestion, the most obvious option is to avoid using pasture with oak trees present. If unavoidable, manually remove acorns daily by hand or with a rake. This can be time consuming, so consider fencing off the oak tree including its branch span to avoid grazing in that area. Ensure supplementary feed is provided if forage is low, to avoid temptation to snack on acorns.
𝐌𝐚𝐢𝐧 𝐜𝐚𝐮𝐬𝐞𝐬 𝐨𝐟 𝐜𝐨𝐧𝐜𝐞𝐫𝐧: Gastroenteritis, Kidney damage
𝐒𝐢𝐠𝐧𝐬 𝐭𝐨 𝐥𝐨𝐨𝐤 𝐨𝐮𝐭 𝐟𝐨𝐫:
- Dull demeanour, depression or lethargy
- Colic
- Loss of appetite
- Increased periods of lying down
- Mouth ulcers
- Blood in urine or faeces
- Diarrhoea or constipation
- Ataxia
𝐓𝐫𝐞𝐚𝐭𝐦𝐞𝐧𝐭: Unfortunately, there is no specific treatment for tannic poisoning. Care given will depend on severity of the symptoms and the stage of the illness but will often include pain relief and intravenous fluid therapy.
Acorn poisoning can be fatal, and we'd advise anyone that suspects their horse of having it to call their vet immediately. As always, early intervention is imperative for a positive prognosis.
If you have any concerns or questions regarding Acorn Poisoning, please call us on 01323 815120 and we can arrange a chat with one of our vets, or email [email protected].