The ergot alkaloids have been linked to abortion (in late gestation), prolonged gestation (mares carrying foals 20 to 27 days
longer than normal), dystocia (prolonged gestation results from fetal-dam size disparity), thickened placenta, increased foal
deaths, retained placenta with secondary endometritis, laminitis and septicemia, agalactia with profound drop in prolactin,
increased mare mortality and, because mares don't have normal udder development, vulvar swelling and other signs of partutrition.
Maintaining endophyte-free pastures and ensuring grains are free from contaminating sclerotium are essential for pregnant
mares. Various treatments, including domperidone, have been used with limited success. It probably is best to avoid exposure
of susceptible pregnant mares in late gestation to endophyte-infected pastures or contaminated screenings or hay.
Most myotoxic plants are highly toxic, killing animals before they develop the histologic changes. Subsequently, diagnosis
is made primarily by documenting exposure and identifying plant fragments or various toxins in the blood, tissues or gastrointestinal
Little is known about poisoned animals that recover. However, they are likely to be cardiac cripples or impaired animals that
do no perform up to their genetic potential.
For some plants, nursing foals are often most susceptible to poisoning and may be poisoned with no evidence of maternal toxicity.
As these plants are readily eaten, identifying potential toxic plants and avoiding exposure is essential.
Dr. Stegelmeier is a researcher at the United States Department of Agriculture's Poisonous Plant Research Laboratory in Ogden,