Fescue Toxicosis in Horses

  • Dee L. Cross


Approximately 688,000 horses in the U.S. graze tall fescue (Hoveland, 1993), and for many years, veterinarians and horse owners have reported reproductive problems in mares that consume tall fescue (Garrett et al., 1980; Villahoz et al., 1984; Poppenga et al., 1984). Bacon et al. (1977) reported the first conclusive evidence of the presence of an endophytic fungus in tall fescue that was later identified as Neotyphodium coenophialum. The endophyte of tall fescue was found to be related to lower weight gains, increased body temperature, rough hair coats, gangrenous necrosis of tissue in feet, tail and ears, and reduced conception rates in cattle, as reviewed by Thompson and Stuedemann (1993). The endophyte of tall fescue is the causative agent for reproductive abnormalities in gravid mares as well (Figure 1)(Monroe et al., 1988). Increased gestation lengths, agalactia, foal and mare mortality, tough and thickened placentas, weak and dysmature foals, and reduced serum prolactin and progesterone levels occurred in mares consuming endophyteinfected (E+) pasture, whereas horses on endophyte-free (E-) pasture appeared normal.


Thyroid Stimulate Hormone Tall Fescue Corticotrophin Release Hormone Ergot Alkaloid Prolactin Secretion 
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Copyright information

© Springer Science+Business Media New York 1997

Authors and Affiliations

  • Dee L. Cross
    • 1
  1. 1.Animal, Dairy, and Veterinary Sciences DepartmentClemson UniversityClemsonUSA

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