Hoof Nutrition Intelligence Hoof Nutrition Intelligence is a twice-a-month web segment that is designed to add to the education of footcare professionals when it comes to effectively feeding the hoof. The goal of this web-exclusive feature is to zero in on specific areas of hoof nutrition and avoid broad-based articles that simply look at the overall equine feeding situation.

Below you will find Part 1 of the latest question and answer installment that you can share with your footcare clients.

Q: Can horses eating poisonous plants lead to serious hoof concerns?

By Buck McColl

A: With over 700 plants, shrubs and trees in the U.S. and Canada that can be toxic to horses, this can be a major concern for owners.

Fortunately, horses naturally avoid most noxious weeds and plants because they are bitter and very unpalatable. When a horse has access to good pasture, hay, grain and water, they will most likely avoid eating harmful plants.

But when pastures are drought stressed, over grazed, under fertilized or not clipped, horses tend to look for something else to eat. Examples include the tendency of horses to eat oak leaves or acorns. Since hay can contain poisonous plants, knowing the source of forage is also important.

Plants that are grown on soils that are high in selenium can cause hoof problems. Black walnut and black locust shavings for bedding must be avoided as these can lead to laminitis concerns.

Poisonous plants affect horses in many ways, as any toxin that is ingested that interferes with normal metabolic activity can cause problems. The resulting metabolic blocks can affect a horse in many ways.

Here are just a few examples of how plants, shrubs and tree toxins can have an impact on horses:

  1. Red maple produces gallic acid that cases lethargy and anemia (breakdown of red blood cells) that reduces oxygen transport.
  2. Black walnut shavings should not be eaten, as the resulting toxins are absorbed through the hoof, causing founder or laminitis.
  3. Yews produce toxins that can interfere with heart action.
  4. Azaleas and rhododendron can lead to diarrhea and heart problems.
  5. St. John’s wort can destroy skin cells.
  6. Mycotoxins and fungi found on plants often cause difficulty in giving birth. For example, fescue poisoning is common in pregnant mares.
  7. The toxins fond in alsike clover can cause liver problems.
  8. Milkweed can case seizures, colic and sometimes death in horses.
  9. Sorghum grass (milo, family) produces cyanide, which can lead to death in horses.
  10. White snake rot can lead to weakness and tremors in horses.

Buck McColl was an equine nutritionist and consultant with Mobile Milling Service in Thomasville, N.C. This item is condensed from an article he wrote entitled,” How Poisonous Plants Cause Hoof Damage” that appeared in the May/June 2010 issue of American Farriers Journal.

Click here to read part 1 of the June 17, 2021, installment of Hoof Nutrition Intelligence: Can horses eating poisonous plants lead to serious hoof concerns? Click here to read more installments of Hoof Nutrition Intelligence.