Fescue Toxicity in Brood Mares

Tall fescue grass is often infected with A. coenophialum fungus. When a broodmare grazes on this infected grass, fescue toxicity can occur. Fescue toxicity must be treated to avoid dangerous pregnancy and delivery complications.

  1. Complications

    • Common problems caused by fescue toxicity in broodmares include thickened and retained placentas, failure to lactate, prolonged gestation and abortion of the foal.

    Prevention

    • The best way to avoid the dangerous outcomes of fescue toxicity is to remove pregnant mares from pastures with fescue grass 60 to 90 days before foaling.

    Fescue Hay

    • Fescue hay can also carry the harmful fungus. If the mare is fed hay in place of pasture grass, feed hay that is cut from pastures without fescue.

    Diagnosis

    • Pasture grass samples can be analyzed to see if the fungus that causes fescue toxicity is present. Because these tests can be unreliable, most veterinarians will treat a mare exposed to fescue regardless of the lab results.

    Treatment

    • The impact of fescue toxicity on a pregnant mare can often be reduced or eliminated with treatment that involves a drug called Domperidone. A mare that has been exposed to fescue grass in the last trimester of her pregnancy should be evaluated by a veterinarian.