Foals with meconium impactions strain to defecate and also show signs of persistent abdominal pain. | Photo: Bonnie Barr

Foaling season is upon us, and owners are preparing for the arrival of their next superstars. After a foal is born, several events must occur to ensure he or she remains healthy. One of the most important is passing meconium. This is the first feces, composed of mucus, amniotic fluid, and sloughed cells from the gastrointestinal (GI) tract. It is typically dark greenish-brown or black and ranges in consistency from firm pellets to sticky paste. Foals usually begin passing meconium in the first hours after birth and shortly after ingesting the mare’s colostrum, which acts as a laxative and a stimulator of GI motility.

Meconium passage is generally complete within 24 hours, but it can take up to 48 hours. It is not atypical for newborn foals, standing or in recumbency (lying down), to strain considerably with an arched back when passing meconium. These attempts should be productive, however.

Male foals and foals born after a prolonged gestation appear to be predisposed to meconium impactions, which can be classified as either high or low. A low impaction is an obstruction of the small colon/rectum at the pelvic inlet (the front entry of the pelvis). A high impaction is found earlier in the GI tract, generally at the transverse or right dorsal colon. Low impactions far outnumber more serious high -impactions. Delayed meconium passage prevents proper digestive movement, with subsequent gas/fluid distension causing abdominal pain