Acorn Poisoning - Horses

Oak Trees Pose a Health Risk to Your Horse?

Acorns are the small fruits, or nuts, of oak trees. They grow in clusters on the branches of the oak, falling to the ground as they mature and grow heavy. In some cases, a storm may cause branches to fall and a significant amount of acorns to come down with them. While many animals in the wild depend on the acorn for their nutritional needs, the acorn poses a toxicity risk to some animals, one of them being horses. A few ingested acorns are harmless to a horse’s system, but large amounts can induce severe illness. This is due to the tannic and gallic acids in the acorn, which cause painful lesions in the mouth, the esophagus, in the gastrointestinal tract, and in the internal organs of the horse. While this is not a constant threat, it is one that must be considered, as there are seasons when this type of poisoning does pose a significant health risk.

Symptoms and Types

Constipation
Pain in the abdomen
Blood in the urine
Kidney damage
Nervous symptoms
Head pressing
Circling
Foundering
Obstructive colic
Milder cases may show signs of colic

Causes

Acorn poisoning is caused by the ingestion of large amounts of acorns, oak leaves, or branches. They are especially harmful when still green, as the tannin acid is at the highest. Acorns are very high in protein, and the sudden ingestion of a large amount of protein can cause a blockage of the intestines. Many times acorns are ingested by accident, and in small amounts they are harmless, especially when combined with the normal roughage of hay and grass. There is anecdotal evidence that some horses develop a liking bordering on addiction for acorns and will actually seek them out, overindulging to the point of illness.

Diagnosis

Diagnosis can be difficult unless you know positively that your horse has been kept in an area where there are large amounts of oak leaves, branches, or acorns. Then it is a bit easier to determine the cause of the poisoning. The symptoms alone can indicate poisoning, even if the type of poison is not necessarily known.