The gestation period for horses is variable and ranges from 11-12 months. Diagnosis of pregnancy is made by rectal examination, ultrasound, and hormonal testing. As pregnancy nears full term, the mare shows more signs indicative of impending birth: enlarged abdomen, development and waxing of the mammary glands. Complications that may occur during pregnancy and birth include:

  • Abortions: caused by viral (Equine Herpesvirus), bacterial, and fungal infections; twinning; and fescue toxicity
  • Dystocia (difficulty giving birth)

o rectovaginal tears range in severity; surgical correction is required to restore normal anatomy


o premature placental separation: often caused by placental inflammation