A premature foal is one that is born before 320 days gestation. The classic premature foal is not only small, but also underdeveloped, and is at increased risk for a variety of conditions.

The term "dysmature" refers to a foal that was born at full-term, but shows signs of prematurity such as floppy ears, silky coat, small size, and crooked limbs. Internally, their lungs, kidneys and immune system may not be functioning normally. These problems are grouped into a condition known as "Dysmaturity Syndrome".

Early veterinary intervention provides the best prognosis for premature and dysmature foals. Even foals that are nursing well and are active are at risk for certain conditions. Joint collapse, for example, needs to be diagnosed early and managed appropriately.