Equine Agalactia Study Guide

Overview and Clinical Importance

Agalactia refers to the complete absence of milk production in a postpartum mare. This condition represents a critical emergency in equine reproduction because foals are born immunologically naive (agammaglobulinemic) and depend entirely on colostrum ingestion within the first 12-24 hours of life for passive transfer of immunoglobulins. The absence of lactation puts the foal at immediate risk for failure of passive transfer (FPT), sepsis, and death.

Agalactia must be differentiated from failure of milk let-down (psychological inhibition of oxytocin release) and hypogalactia (insufficient milk production). While all three conditions compromise foal nutrition and immunity, their underlying pathophysiology and treatment differ significantly. On the NAVLE, agalactia is most commonly associated with fescue toxicosis in the southeastern United States.

Mammary Gland Anatomy and Lactation Physiology

Equine Udder Anatomy

The equine udder comprises one pair of mammae located in the inguinal region. Each mamma is drained by two independent mammary ductal trees, resulting in two orifices per teat. This anatomical arrangement differs from cattle (one ductal system per mamma) and represents an important consideration during intramammary treatment.