Are Acorns Harmful to Horses If Eaten?

As lovely as oak trees are, the acorns they produce are indeed toxic to horses. Acorns are naturally bitter because of the amount of tannin present, which normally deters horses. But on occasion, horses have been known to develop a taste for acorns. Good nutrition and optimal pasture conditions can help curb a horse's taste for unsafe plants and trees.

  1. Prevention

    • Horse farms may choose to keep or remove oak trees for various reasons. While cutting down trees may not be an option to prevent poisoning, fencing that extends far enough out around the trunk of the tree to include the acorn drop area is necessary. A safer option is to prevent horses from coming in contact with the same pasture area at all. Cutting and removing low-hanging branches and keeping fields free from leaves and debris also reduce the risk of ingestion.

    Symptoms

    • Unlike the yew tree, where as few as 8 oz. will kill a horse within minutes, an occasional acorn should not harm a normally healthy horse. However, green acorns, buds and spring leaves have higher amounts of tannin than older leaves and mature acorns and should thus be avoided. Excessive salivation, loss of appetite, constipation and diarrhea are symptoms of toxic levels of acorns. Mouth ulcers, kidney failure and blood in the urine and fecal matter are long-term effects of excessive ingestion of acorns.

    Treatment

    • If a horse has eaten a toxic plant or is showing signs of being poisoned, then contact a veterinarian immediately. Some horses are extremely sensitive to tannin, which means that acorns in any amount can be fatal. Knowing how much toxin has been ingested as well as how long the horse has been ingesting acorns is necessary for proper treatment. The level of toxicity and organ damage the horse suffers will determine the the level and type of treatment a veterinarian will administer.

    Considerations

    • Lack of pasture or grazing space may tempt horses into eating toxic foods.

      Not all horses will ingest or feed on acorns because of the bitterness they leave on the tongue. If a horse seeks out acorns as a food source, then consider contacting a veterinarian to ensure the horse is not missing nutritional needs. Foods that are old, improperly stored or contaminated are devoid of nutritional value and can be fatal. Make sure a quality pasture and fresh grass hay, along with clean water, are available to horses at all times.